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iOS (formerly iPhone OS) is a
mobile operating system A mobile operating system is an operating system for mobile phones, tablets, smartwatches, smartglasses, or other non-laptop personal mobile computing devices. While computers such as typical laptops are "mobile", the operating systems used on ...
created and developed by
Apple Inc. Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company ...
exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also includes the system software for
iPad The iPad is a brand of iOS and iPadOS-based tablet computers that are developed by Apple Inc. The iPad was conceived before the related iPhone but the iPhone was developed and released first. Speculation about the development, operating s ...
s predating
iPadOS iPadOS is a mobile operating system developed by Apple Inc. for its iPad line of tablet computers. It is a rebranded variant of iOS, the operating system used by Apple's iPhones, renamed to reflect the diverging features of the two product l ...
—which was introduced in 2019—as well as on the
iPod Touch The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music pl ...
devices—which were discontinued in mid-2022. It is the world's second-most widely installed mobile operating system, after Android. It is the basis for three other operating systems made by Apple: iPadOS,
tvOS tvOS (formerly known as Apple TV Software) is an operating system developed by Apple Inc. for the Apple TV, a digital media player. In the first-generation Apple TV, Apple TV Software was based on Mac OS X. Starting with the second-generation ...
, and
watchOS watchOS is the operating system of the Apple Watch, developed by Apple Inc. It is based on iOS, the operating system used by the iPhone, and has many similar features. It was released on April 24, 2015, along with the Apple Watch, the only dev ...
. It is proprietary software, although some parts of it are open source under the
Apple Public Source License The Apple Public Source License (APSL) is the open-source and free software license under which Apple's Darwin operating system was released in 2000. A free and open-source software license was voluntarily adopted to further involve the communit ...
and other licenses. Unveiled in 2007 for the first-generation iPhone, iOS has since been extended to support other Apple devices such as the
iPod Touch The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music pl ...
(September 2007) and the iPad (introduced: January 2010; availability: April 2010.) , Apple's
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
contains more than 2.1 million iOS applications, 1 million of which are native for iPads. These
mobile app A mobile application or app is a computer program or software application designed to run on a mobile device such as a phone, tablet, or watch. Mobile applications often stand in contrast to desktop applications which are designed to run on d ...
s have collectively been downloaded more than 130 billion times. Major versions of iOS are released annually. The current stable version,
iOS 16 iOS 16 is the 16th and current major release of the iOS mobile operating system developed by Apple for its iPhone line of products. It was announced at the company's Worldwide Developers Conference (WWDC) on June 6, 2022, as the successor to ...
, was released to the public on September 12, 2022.


History

In 2005, when
Steve Jobs Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; a ...
began planning the iPhone, he had a choice to either "shrink the Mac, which would be an epic feat of engineering, or enlarge the iPod". Jobs favored the former approach but pitted the
Macintosh The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc., Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and ...
and
iPod The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes ...
teams, led by
Scott Forstall Scott James Forstall (born 1969) is an American software engineer, known for leading the original software development team for the iPhone and iPad, and Broadway producer, known for co-producing the Tony award-winning '' Fun Home'' and '' Eclips ...
and
Tony Fadell Anthony Michael Fadell (born March 22, 1969) is an American engineer, designer, entrepreneur, and investor. He was senior vice president of the iPod division at Apple Inc. and founder and former CEO of Nest Labs. Fadell joined Apple Inc. in 20 ...
, respectively, against each other in an internal competition, with Forstall winning by creating the iPhone OS. The decision enabled the success of the iPhone as a platform for third-party developers: using a well-known desktop operating system as its basis allowed the many third-party Mac developers to write software for the iPhone with minimal retraining. Forstall was also responsible for creating a
software development kit A software development kit (SDK) is a collection of software development tools in one installable package. They facilitate the creation of applications by having a compiler, debugger and sometimes a software framework. They are normally specific to ...
for programmers to build iPhone apps, as well as an
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
within
iTunes iTunes () is a software program that acts as a media player, media library, mobile device management utility, and the client app for the iTunes Store. Developed by Apple Inc., it is used to purchase, play, download, and organize digital mul ...
. The operating system was unveiled with the iPhone at the
Macworld Conference & Expo Macworld/iWorld was an information technology trade show with conference tracks dedicated to the Apple Macintosh platform. It was held annually in the United States during January. Originally ''Macworld Expo'' and then ''Macworld Conference & Expos ...
on January 9, 2007, and released in June of that year. At the time of its unveiling in January, Steve Jobs claimed: "iPhone runs OS X" and runs "desktop class applications", but at the time of the iPhone's release, the operating system was renamed "iPhone OS". Initially, third-party native applications were not supported. Jobs' reasoning was that developers could build
web application A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serve ...
s through the Safari web browser that "would behave like native apps on the iPhone". In October 2007, Apple announced that a native Software Development Kit (SDK) was under development and that they planned to put it "in developers' hands in February". On March 6, 2008, Apple held a press event, announcing the iPhone SDK. The
iOS App Store The App Store is an app store platform, developed and maintained by Apple Inc., for mobile apps on its iOS and iPadOS operating systems. The store allows users to browse and download approved apps developed within Apple's iOS Software Deve ...
was opened on July 10, 2008, with an initial 500 applications available. This quickly grew to 3,000 in September 2008, 15,000 in January 2009, 50,000 in June 2009, 100,000 in November 2009, 250,000 in August 2010, 650,000 in July 2012, 1 million in October 2013, 2 million in June 2016, and 2.2 million in January 2017. , 1 million apps are natively compatible with the
iPad The iPad is a brand of iOS and iPadOS-based tablet computers that are developed by Apple Inc. The iPad was conceived before the related iPhone but the iPhone was developed and released first. Speculation about the development, operating s ...
tablet computer. These apps have collectively been downloaded more than 130 billion times. App intelligence firm Sensor Tower estimated that the App Store would reach 5 million apps by 2020. In September 2007, Apple announced the
iPod Touch The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music pl ...
, a redesigned
iPod The iPod is a discontinued series of portable media players and multi-purpose mobile devices designed and marketed by Apple Inc. The first version was released on October 23, 2001, about months after the Macintosh version of iTunes ...
based on the iPhone form factor. On January 27, 2010, Apple introduced their much-anticipated media tablet, the
iPad The iPad is a brand of iOS and iPadOS-based tablet computers that are developed by Apple Inc. The iPad was conceived before the related iPhone but the iPhone was developed and released first. Speculation about the development, operating s ...
, featuring a larger screen than the iPhone and iPod Touch, and designed for web browsing, media consumption, and reading, and offering multi-touch interaction with multimedia formats including newspapers, e-books, photos, videos, music, word processing documents, video games, and most existing iPhone apps using a 9.7-inch screen. It also includes a mobile version of Safari for web browsing, as well as access to the App Store,
iTunes iTunes () is a software program that acts as a media player, media library, mobile device management utility, and the client app for the iTunes Store. Developed by Apple Inc., it is used to purchase, play, download, and organize digital mul ...
Library,
iBookstore Apple Books (formerly known as iBooks between January 2010 and September 2018) is an e-book reading and store application by Apple Inc. for its iOS and macOS operating systems and devices. It was announced, under the name iBooks, in conjunctio ...
, Contacts, and Notes. Content is downloadable via
Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wave ...
and optional 3G service or synced through the user's computer.
AT&T AT&T Inc. is an American multinational telecommunications holding company headquartered at Whitacre Tower in Downtown Dallas, Texas. It is the world's largest telecommunications company by revenue and the third largest provider of mobile tel ...
was initially the sole U.S. provider of 3G wireless access for the iPad. In June 2010, Apple rebranded iPhone OS as "iOS". The trademark "IOS" had been used by
Cisco Cisco Systems, Inc., commonly known as Cisco, is an American-based multinational digital communications technology conglomerate corporation headquartered in San Jose, California. Cisco develops, manufactures, and sells networking hardware, ...
for over a decade for its operating system,
IOS iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also include ...
, used on its routers. To avoid any potential lawsuit, Apple licensed the "IOS" trademark from Cisco. The
Apple Watch Apple Watch is a line of smartwatches produced by Apple Inc. It incorporates fitness tracking, health-oriented capabilities, and wireless telecommunication, and integrates with iOS and other Apple products and services. The Apple Watch was rel ...
smartwatch A smartwatch is a wearable computer in the form of a watch; modern smartwatches provide a local touchscreen interface for daily use, while an associated smartphone app provides management and telemetry, such as long-term biomonitoring. While ea ...
was announced by Tim Cook on September 9, 2014, being introduced as a product with health and fitness-tracking. It was released on April 24, 2015. It uses
watchOS watchOS is the operating system of the Apple Watch, developed by Apple Inc. It is based on iOS, the operating system used by the iPhone, and has many similar features. It was released on April 24, 2015, along with the Apple Watch, the only dev ...
as its operating system; watchOS is based on iOS, with new features created specially for the Apple Watch such as an activity tracking app. On November 22, 2016, a five-second video file originally named "IMG_0942.MP4" started crashing iOS on an increasing count of devices, forcing users to reboot. It gained massive popularity through social media channels and messaging services. In October 2016, Apple opened its first iOS Developer Academy in
Naples Naples (; it, Napoli ; nap, Napule ), from grc, Νεάπολις, Neápolis, lit=new city. is the regional capital of Campania and the third-largest city of Italy, after Rome and Milan, with a population of 909,048 within the city's adminis ...
inside
University of Naples Federico II The University of Naples Federico II ( it, Università degli Studi di Napoli Federico II) is a public university in Naples, Italy. Founded in 1224, it is the oldest public non-sectarian university in the world, and is now organized into 26 depar ...
's new campus. The course is completely free, aimed at acquiring specific technical skills on the creation and management of applications for the Apple ecosystem platforms. At the academy there are also issues of
business administration Business administration, also known as business management, is the administration of a commercial enterprise. It includes all aspects of overseeing and supervising the business operations of an organization. From the point of view of management ...
(business planning and business management with a focus on digital opportunities) and there is a path dedicated to the design of graphical interfaces. Students have the opportunity to participate in the "Enterprise Track", an in-depth training experience on the entire life cycle of an app, from design to implementation, to security,
troubleshooting Troubleshooting is a form of problem solving, often applied to repair failed products or processes on a machine or a system. It is a logical, systematic search for the source of a problem in order to solve it, and make the product or process ope ...
, data storage and cloud usage. As of 2020, the academy graduated almost a thousand students from all over the world, who have worked on 400 app ideas and have already published about 50 apps on the iOS
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
. In the 2018–2019 academic year, students from more than 30 countries arrived. 35 of these have been selected to attend the Worldwide Developer Conference, the annual Apple Developer Conference held annually in California in early June. On June 3, 2019,
iPadOS iPadOS is a mobile operating system developed by Apple Inc. for its iPad line of tablet computers. It is a rebranded variant of iOS, the operating system used by Apple's iPhones, renamed to reflect the diverging features of the two product l ...
, the branded version of iOS for iPad, was announced at the 2019 WWDC; it was launched on September 25, 2019.


Features


Interface

The iOS
user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
is based upon
direct manipulation In computer science, human–computer interaction, and interaction design, direct manipulation is an approach to interfaces which involves continuous representation of objects of interest together with rapid, reversible, and incremental action ...
, using
multi-touch In computing, multi-touch is technology that enables a surface (a touchpad or touchscreen) to recognize the presence of more than one somatosensory system, point of contact with the surface at the same time. The origins of multitouch began at CER ...
gestures such as ''swipe'', ''tap'', ''pinch'', and ''reverse pinch''. Interface control elements include sliders, switches, and buttons. Internal
accelerometer An accelerometer is a tool that measures proper acceleration. Proper acceleration is the acceleration (the rate of change of velocity) of a body in its own instantaneous rest frame; this is different from coordinate acceleration, which is accele ...
s are used by some applications to respond to shaking the device (one common result is the
undo Undo is an interaction technique which is implemented in many computer programs. It erases the last change done to the document, reverting it to an older state. In some more advanced programs, such as graphic processing, undo will negate the las ...
command) or rotating it in
three dimensions Three-dimensional space (also: 3D space, 3-space or, rarely, tri-dimensional space) is a geometric setting in which three values (called ''parameters'') are required to determine the position of an element (i.e., point). This is the informa ...
(one common result is switching between portrait and landscape mode). Various
accessibility Accessibility is the design of products, devices, services, vehicles, or environments so as to be usable by people with disabilities. The concept of accessible design and practice of accessible development ensures both "direct access" (i. ...
described in functions enable users with vision and hearing disabilities to properly use iOS. iOS devices boot to the homescreen, the primary navigation and information "hub" on iOS devices, analogous to the
desktop A desktop traditionally refers to: * The surface of a desk (often to distinguish office appliances that fit on a desk, such as photocopiers and printers, from larger equipment covering its own area on the floor) Desktop may refer to various compu ...
found on personal computers. iOS homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content, such as a
weather forecast Weather forecasting is the application of science and technology to predict the conditions of the atmosphere for a given location and time. People have attempted to predict the weather informally for millennia and formally since the 19th centu ...
, the user's email inbox, or a
news ticker A news ticker (sometimes called a "crawler", "crawl", "slide", "zipper", or "ticker tape") is a horizontal or vertical (depending on a language's writing system) text-based display either in the form of a graphic that typically resides in the lo ...
directly on the homescreen. Along the top of the screen is a status bar, showing information about the device and its connectivity. The status bar itself contains two elements, the Control Center and the
Notification Center Notification Center is a feature in iOS and macOS that provides an overview of alerts from applications. It displays notifications until the user completes an associated action, rather than requiring instant resolution. Users may choose what a ...
. The Control Center can be "pulled" down from the top right of the notch, on the new iPhones, giving access to various toggles to manage the device more quickly without having to open the Settings. It is possible to manage brightness, volume, wireless connections, music player, etc. Instead, scrolling from the top left to the bottom will open the
Notification Center Notification Center is a feature in iOS and macOS that provides an overview of alerts from applications. It displays notifications until the user completes an associated action, rather than requiring instant resolution. Users may choose what a ...
, which in the latest versions of iOS is very similar to the lockscreen. It displays notifications in chronological order and groups them by application. From the notifications of some apps it is possible to interact directly, for example by replying a message directly from it. Notifications are sent in two modes, the important notifications that are displayed on the lock screen and signaled by a distinctive sound, accompanied by a warning banner and the app badge icon, and the secondary mode where they are displayed in the Notification Center, but they are not shown on the lock screen, nor are they indicated by warning banners, badge icons or sounds. On earlier iPhones with
home button A home, or domicile, is a space used as a permanent or semi-permanent residence for one or many humans, and sometimes various companion animals. It is a fully or semi sheltered space and can have both interior and exterior aspects to it. H ...
,
screenshot screenshot (also known as screen capture or screen grab) is a digital image that shows the contents of a computer display. A screenshot is created by the operating system or software running on the device powering the display. Additionally, s ...
s can be created with the simultaneous press of the
home A home, or domicile, is a space used as a permanent or semi-permanent residence for one or many humans, and sometimes various companion animals. It is a fully or semi sheltered space and can have both interior and exterior aspects to it. H ...
and power buttons. In comparison to
Android OS Android is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of deve ...
, which requires the buttons to be held down, a short press does suffice on iOS. On the more recent iPhones which lack a physical home button, screenshots are captured using the volume-up and power buttons instead. The camera application used a skeuomorphic closing camera shutter animation prior to iOS 7. Since then, it uses a simple short blackout effect. Notable additions over time include HDR photography and the option to save both normal and high dynamic range photographs simultaneously where the former prevents ghosting effects from moving objects (since iPhone 5,
iOS 6 iOS 6 is the sixth major release of the iOS mobile operating system developed by Apple Inc, being the successor to iOS 5. It was announced at the company's Worldwide Developers Conference on June 11, 2012, and was released on September 19, 2 ...
), automatic HDR adjustment (
iOS 7.1 iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 ...
), "live photo" with short video bundled to each photo if enabled ( iPhone 6s,
iOS 9 iOS 9 is the ninth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 8. It was announced at the company's Worldwide Developers Conference on June 8, 2015, and was released on September 16, ...
), and a
digital zoom Digital zoom is a method of decreasing the precise angle of view of a digital photograph or video image. It is accomplished by cropping an image down to an area with the same aspect ratio as the original, and scaling the image up to the dimen ...
shortcut (
iPhone 7 Plus The iPhone 7 and iPhone 7 Plus are smartphones that were designed, developed, and marketed by Apple Inc. They are the tenth generation of the iPhone. They were announced on September 7, 2016, at the Bill Graham Civic Auditorium in San Fran ...
,
iOS 10 iOS 10 is the iOS version history, tenth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 9. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers Conf ...
). Some camera settings such as video resolution and frame rate are not adjustable through the camera interface itself, but are outsourced to the system settings. A new feature in
iOS 13 iOS 13 is the thirteenth major release of the iOS mobile operating system developed by Apple Inc. for their iPhone, iPod Touch, and HomePod lines. The successor to iOS 12 on those devices, it was announced at the company's Worldwide Developer ...
called "context menus" shows related actions when you touch and hold an item. When the context menu is displayed, the background is blurred. To choose from a few options, a selection control is used. Selectors can appear anchored at the bottom or in line with the content (called date selectors). Date selectors take on the appearance of any other selection control, but with a column for day, month, and optionally year. Alerts appear in the center of the screen, but there are also alerts that scroll up from the bottom of the screen (called "action panels"). Destructive actions (such as eliminating any element) are colored red. The official font of iOS is
San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
. It is designed for small text readability, and is used throughout the operating system, including third-party apps. The icons are 180x180px in size for iPhones with a larger screen, usually models over 6 inches, including
iPhone 11 Pro The iPhone 11 Pro and iPhone 11 Pro Max are smartphones designed, developed and marketed by Apple Inc. Serving as the Apple's flagship models of the List of iOS devices, 13th-generation of iPhones, they succeeded the iPhone XS and iPhone XS M ...
and
iPhone 8 Plus The iPhone 8 and iPhone 8 Plus are smartphones designed, developed, and marketed by Apple Inc. They along with the iPhone X make up the 11th generation of the iPhone. The iPhone 8 was released on September 22, 2017, succeeding the iPhone 7 and ...
, while it's 120x120px on iPhones with smaller displays.


Applications

iOS devices come with preinstalled apps developed by Apple including Mail, Maps, TV, Music, FaceTime, Wallet, Health, and many more. Applications (" apps") are the most general form of application
software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...
that can be installed on iOS. They are downloaded from the official catalog of the
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
digital store, where apps are subjected to security checks before being made available to users. In June 2017, Apple updated its guidelines to specify that app developers will no longer have the ability to use custom prompts for encouraging users to leave reviews for their apps. IOS applications can also be installed directly from an IPA file provided by the software distributor, via unofficial ways. They are written using iOS Software Development Kit (SDK) and, often, combined with
Xcode Xcode is Apple's integrated development environment (IDE) for macOS, used to develop software for macOS, iOS, iPadOS, watchOS, and tvOS. It was initially released in late 2003; the latest stable release is version 14.2, released on December 13, ...
, using officially supported programming languages, including
Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...
and
Objective-C Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTS ...
. Other companies have also created tools that allow for the development of native iOS apps using their respective programming languages. Applications for iOS are mostly built using components of
UIKit Cocoa Touch is the application development environment for building software programs to run on iOS for the iPhone and iPod Touch, iPadOS for the iPad, watchOS for the Apple Watch, and tvOS for the Apple TV, from Apple Inc. Cocoa Touch provid ...
, a programming framework. It allows applications to have a consistent look and feel with the OS, nevertheless offering customization. Elements automatically update along with iOS updates, automatically including new interface rules. UIKit elements are very adaptable, this allows developers to design a single app that looks the same on any iOS device. In addition to defining the iOS interface, UIKit defines the functionality of the application. At first, Apple did not intend to release an SDK to developers, because they did not want third-party apps to be developed for iOS, building
web apps A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serve ...
instead. However, this technology never entered into common use, this led Apple to change its opinion, so in October 2007 the SDK for developers was announced, finally released on March 6, 2008. The SDK includes an inclusive set of development tools, including an audio mixer and an iPhone simulator. It is a free download for Mac users. It is not available for
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
PCs. To test the application, get technical support, and distribute applications through
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
, developers are required to subscribe to the Apple Developer Program. Over the years, the Apple Store apps surpassed multiple major milestones, including 50,000, 100,000, 250,000, 500,000, 1 million, and 2 million apps. The billionth application was installed on April 24, 2009.


Home screen

The home screen, rendered by
SpringBoard A springboard or diving board is used for diving and is a board that is itself a spring, i.e. a linear flex-spring, of the cantilever type. Springboards are commonly fixed by a hinge at one end (so they can be flipped up when not in use), and ...
, displays application icons and a dock at the bottom where users can pin their most frequently used apps. The home screen appears whenever the user unlocks the device, presses the physical "Home" button while in an app, or swipes up from the bottom of the screen using the home bar. Before iOS 4 on the iPhone 3GS (or later), the screen's background could be customized only through jailbreaking, but can now be changed out-of-the-box. The screen has a status bar across the top to display data, such as time, battery level, and signal strength. The rest of the screen is devoted to the current application. When a passcode is set and a user switches on the device, the passcode must be entered at the Lock Screen before access to the Home screen is granted. In iPhone OS 3,
Spotlight Spotlight or spot light may refer to: Lighting * Spot lights, automotive auxiliary lamps * Spotlight (theatre lighting) * Spotlight, a searchlight * Stage lighting instrument, stage lighting instruments, of several types Art, entertainment, an ...
was introduced, allowing users to search media, apps, emails, contacts, messages, reminders, calendar events, and similar content. In iOS 7 and later, Spotlight is accessed by pulling down anywhere on the home screen (except for the top and bottom edges that open Notification Center and Control Center). In iOS 9, there are two ways to access Spotlight. As with iOS 7 and 8, pulling down on any homescreen will show Spotlight. However, it can also be accessed as it was in iOS versions 3 through 6. This endows Spotlight with Siri suggestions, which include app suggestions, contact suggestions and news. In iOS 10, Spotlight is at the top of the now-dedicated "Today" panel. Since iOS 3.2, users are able to set a background image for the Home Screen. This feature is only available on third-generation devices— iPhone 3GS, third-generation
iPod Touch The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music pl ...
(iOS 4.0 or newer), and all iPad models (since iOS 3.2)—or newer.
iOS 7 iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 o ...
introduced a parallax effect on the Home Screen, which shifts the device's wallpaper and icons in response to the movement of the device, creating a 3D effect and an illusion of floating icons. This effect is also visible in the tab view of Mail and Safari. Researchers found that users organize icons on their homescreens based on usage frequency and relatedness of the applications, as well as for reasons of usability and aesthetics.


System font

iOS originally used
Helvetica Helvetica (originally Neue Haas Grotesk) is a widely used sans-serif typeface developed in 1957 by Swiss typeface designer Max Miedinger and Eduard Hoffmann. Helvetica is a neo-grotesque design, one influenced by the famous 19th century (1890s) ...
as the system font. Apple switched to
Helvetica Neue Helvetica (originally Neue Haas Grotesk) is a widely used sans-serif typeface developed in 1957 by Swiss typeface designer Max Miedinger and Eduard Hoffmann. Helvetica is a neo-grotesque design, one influenced by the famous 19th century (1890s) ...
exclusively for the
iPhone 4 The iPhone 4 is a smartphone that was designed and marketed by Apple Inc. It is the fourth generation of the iPhone lineup, succeeding the iPhone 3GS and preceding the 4S. Following a number of notable leaks, the iPhone 4 was first unvei ...
and its Retina Display, and retained Helvetica as the system font for older iPhone devices on iOS 4. With iOS 7, Apple announced that they would change the system font to Helvetica Neue Light, a decision that sparked criticism for inappropriate usage of a light, thin typeface for low-resolution mobile screens. Apple eventually chose Helvetica Neue instead. The release of iOS 7 also introduced the ability to scale text or apply other forms of text accessibility changes through Settings. With iOS 9, Apple changed the font to
San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
, an Apple-designed font aimed at maximum legibility and font consistency across its product lineup.


Folders

iOS 4 introduced folders, which can be created by dragging an application on top of another, and from then on, more items can be added to the folder using the same procedure. A title for the folder is automatically selected by the category of applications inside, but the name can also be edited by the user. When apps inside folders receive notification badges, the individual numbers of notifications are added up and the total number is displayed as a notification badge on the folder itself. Originally, folders on an iPhone could include up to 12 apps, while folders on iPad could include 20. With increasing display sizes on newer iPhone hardware, iOS 7 updated the folders with pages similar to the home screen layout, allowing for a significant expansion of folder functionality. Each page of a folder can contain up to nine apps, and there can be 15 pages in total, allowing for a total of 135 apps in a single folder. In iOS 9, Apple updated folder sizes for iPad hardware, allowing for 16 apps per page, still at 15 pages maximum, increasing the total to 240 apps.


Notification Center

Before iOS 5, notifications were delivered in a
modal window In user interface design for computer applications, a modal window is a graphical control element subordinate to an application's main window. A modal window creates a mode that disables the main window but keeps it visible, with the modal window ...
and couldn't be viewed after being dismissed. In iOS 5, Apple introduced
Notification Center Notification Center is a feature in iOS and macOS that provides an overview of alerts from applications. It displays notifications until the user completes an associated action, rather than requiring instant resolution. Users may choose what a ...
, which allows users to view a history of notifications. The user can tap a notification to open its corresponding app, or clear it. Notifications are now delivered in banners that appear briefly at the top of the screen. If a user taps a received notification, the application that sent the notification will be opened. Users can also choose to view notifications in modal alert windows by adjusting the application's notification settings. Introduced with iOS 8, widgets are now accessible through the Notification Center, defined by 3rd parties. When an app sends a notification while closed, a red badge appears on its icon. This badge tells the user, at a glance, how many notifications that app has sent. Opening the app clears the badge.


Accessibility

iOS offers various accessibility features to help users with vision and hearing disabilities. One major feature,
VoiceOver Voice-over (also known as off-camera or off-stage commentary) is a production technique where a voice—that is not part of the narrative (non-diegetic)—is used in a radio, television production, filmmaking, theatre, or other presentations. ...
, provides a voice reading information on the screen, including contextual buttons, icons, links and other
user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...
elements, and allows the user to navigate the operating system through gestures. Any apps with default controls and developed with a UIKit
framework A framework is a generic term commonly referring to an essential supporting structure which other things are built on top of. Framework may refer to: Computing * Application framework, used to implement the structure of an application for an op ...
gets VoiceOver functionality built in. One example includes holding up the iPhone to take a photo, with VoiceOver describing the photo scenery. As part of a "Made for iPhone" program, introduced with the release of
iOS 7 iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 o ...
in 2013, Apple has developed technology to use
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
and a special technology protocol to let compatible third-party equipment connect with iPhones and iPads for streaming audio directly to a user's ears. Additional customization available for Made for iPhone products include battery tracking and adjustable sound settings for different environments. Apple made further efforts for accessibility for the release of
iOS 10 iOS 10 is the iOS version history, tenth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 9. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers Conf ...
in 2016, adding a new pronunciation editor to VoiceOver, adding a Magnifier setting to enlarge objects through the device's camera, software TTY support for deaf people to make phone calls from the iPhone, and giving tutorials and guidelines for third-party developers to incorporate proper accessibility functions into their apps. In 2012, Liat Kornowski from ''
The Atlantic ''The Atlantic'' is an American magazine and multi-platform publisher. It features articles in the fields of politics, foreign affairs, business and the economy, culture and the arts, technology, and science. It was founded in 1857 in Boston, ...
'' wrote that "the iPhone has turned out to be one of the most revolutionary developments since the invention of
Braille Braille (Pronounced: ) is a tactile writing system used by people who are visually impaired, including people who are Blindness, blind, Deafblindness, deafblind or who have low vision. It can be read either on Paper embossing, embossed paper ...
", and in 2016, Steven Aquino of ''
TechCrunch TechCrunch is an American online newspaper focusing on high tech and startup companies. It was founded in June 2005 by Archimedes Ventures, led by partners Michael Arrington and Keith Teare. In 2010, AOL acquired the company for approximately ...
'' described Apple as "leading the way in assistive technology", with Sarah Herrlinger, Senior Manager for Global Accessibility Policy and Initiatives at Apple, stating that "We see accessibility as a basic human right. Building into the core of our products supports a vision of an inclusive world where opportunity and
access to information Access may refer to: Companies and organizations * ACCESS (Australia), an Australian youth network * Access (credit card), a former credit card in the United Kingdom * Access Co., a Japanese software company * Access Healthcare, an Indian BPO se ...
are barrier-free, empowering individuals with disabilities to achieve their goals". Criticism has been aimed at iOS depending on both internet connection (either WiFi or through iTunes) and a working
SIM card file:SIM-Karte von Telefónica O2 Europe - Standard und Micro.jpg, A typical SIM card (mini-SIM with micro-SIM cutout) file:Sim card.png, A smart card taken from a Global System for Mobile Communications, GSM mobile phone file:Simkarte NFC SecureE ...
upon first activation. This restriction has been loosened in iOS 12, which no longer requires the latter.


Multitasking

Multitasking for iOS was first released in June 2010 along with the release of
iOS 4 iOS 4 is the fourth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iPhone OS 3. It was announced at the Apple Special Event on April 8, 2010, and was released on June 21, 2010. iOS 4 is the fi ...
. Only certain devices—
iPhone 4 The iPhone 4 is a smartphone that was designed and marketed by Apple Inc. It is the fourth generation of the iPhone lineup, succeeding the iPhone 3GS and preceding the 4S. Following a number of notable leaks, the iPhone 4 was first unvei ...
, iPhone 3GS, and
iPod Touch The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music pl ...
3rd generation—were able to multitask. The
iPad The iPad is a brand of iOS and iPadOS-based tablet computers that are developed by Apple Inc. The iPad was conceived before the related iPhone but the iPhone was developed and released first. Speculation about the development, operating s ...
did not get multitasking until iOS 4.2.1 in that November. The implementation of multitasking in iOS has been criticized for its approach, which limits the work that applications in the background can perform to a limited function set and requires application developers to add explicit support for it. Before iOS 4, multitasking was limited to a selection of the applications Apple included on the device. Users could however "jailbreak" their device in order to unofficially multitask. Starting with iOS 4, on third-generation and newer iOS devices, multitasking is supported through seven background APIs: # Background audio – application continues to run in the background as long as it is playing audio or video content # Voice over IP – application is suspended when a phone call is not in progress # Background location – application is notified of location changes #
Push notifications Push technology or server push is a style of Internet-based communication where the request for a given transaction is initiated by the publisher or central server. It is contrasted with pull/get, where the request for the transmission of informat ...
# Local notifications – application schedules local notifications to be delivered at a predetermined time # Task completion – application asks the system for extra time to complete a given task # Fast app switching – application does not execute any code and may be removed from memory at any time In iOS 5, three new background APIs were introduced: # Newsstand – application can download content in the background to be ready for the user # External Accessory – application communicates with an external accessory and shares data at regular intervals # Bluetooth Accessory – application communicates with a bluetooth accessory and shares data at regular intervals In iOS 7, Apple introduced a new multitasking feature, providing all apps with the ability to perform background updates. This feature prefers to update the user's most frequently used apps and prefers to use Wi-Fi networks over a cellular network, without markedly reducing the device's battery life.


Switching applications

In iOS 4.0 to iOS 6.x, double-clicking the home button activates the application switcher. A scrollable dock-style interface appears from the bottom, moving the contents of the screen up. Choosing an icon switches to an application. To the far left are icons which function as music controls, a rotation lock, and on iOS 4.2 and above, a volume controller. With the introduction of iOS 7, double-clicking the home button also activates the application switcher. However, unlike previous versions it displays screenshots of open applications on top of the icon and horizontal scrolling allows for browsing through previous apps, and it is possible to close applications by dragging them up, similar to how
WebOS webOS, also known as LG webOS and previously known as Open webOS, HP webOS and Palm webOS, is a Linux kernel-based multitasking operating system for smart devices such as smart TVs that has also been used as a mobile operating system. Initially ...
handled multiple cards. With the introduction of iOS 9, the application switcher received a significant visual change; while still retaining the card metaphor introduced in iOS 7, the application icon is smaller, and appears above the screenshot (which is now larger, due to the removal of "Recent and Favorite Contacts"), and each application "card" overlaps the other, forming a
rolodex A Rolodex is a rotating card file device used to store business contact information. Its name, a portmanteau of the words ''rolling'' and ''index'', has become somewhat genericized (usually as ''rolodex'') for any personal organizer performing thi ...
effect as the user scrolls. Now, instead of the home screen appearing at the leftmost of the application switcher, it appears rightmost. In
iOS 11 iOS 11 is the iOS version history, eleventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 10. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers C ...
, the application switcher receives a major redesign. In the iPad, the Control Center and app switcher are combined. The app switcher in the iPad can also be accessed by swiping up from the bottom. In the iPhone, the app switcher cannot be accessed if there are no apps in the
RAM Ram, ram, or RAM may refer to: Animals * A male sheep * Ram cichlid, a freshwater tropical fish People * Ram (given name) * Ram (surname) * Ram (director) (Ramsubramaniam), an Indian Tamil film director * RAM (musician) (born 1974), Dutch * ...
.


Ending tasks

In iOS 4.0 to iOS 6.x, briefly holding the icons in the application switcher makes them "jiggle" (similarly to the homescreen) and allows the user to ''force'' quit the applications by tapping the red minus circle that appears at the corner of the app's icon. Clearing applications from multitasking stayed the same from iOS 4.0 through 6.1.6, the last version of iOS 6. As of iOS 7, the process has become faster and easier. In iOS 7, instead of holding the icons to close them, they are closed by simply swiping them upwards off the screen. Up to three apps can be cleared at a time compared to one in versions up to iOS 6.1.6.


Task completion

Task completion allows apps to continue a certain task after the app has been suspended. As of iOS 4.0, apps can request up to ten minutes to complete a task in the background. This doesn't extend to background uploads and downloads though (e.g. if a user starts a download in one application, it won't finish if they switch away from the application).


Siri

Siri () is an
intelligent personal assistant An intelligent virtual assistant (IVA) or intelligent personal assistant (IPA) is a software agent that can perform tasks or services for an individual based on commands or questions. The term "chatbot" is sometimes used to refer to virtual ...
integrated into iOS. The assistant uses voice queries and a
natural language user interface Natural-language user interface (LUI or NLUI) is a type of computer human interface where linguistic phenomena such as verbs, phrases and clauses act as UI controls for creating, selecting and modifying data in software applications. In interface d ...
to answer questions, make recommendations, and perform actions by delegating requests to a set of Internet services. The software adapts to users' individual language usages, searches, and preferences, with continuing use. Returned results are individualized. Originally released as an app for iOS in February 2010, it was acquired by Apple two months later, and then integrated into
iPhone 4S The iPhone 4S (originally styled as iPhone 4 S, retroactively stylized with a lowercase 's' as iPhone 4s as of September 2013) is a smartphone that was designed and marketed by Apple Inc. It is the List of iOS devices, fifth generation o ...
at its release in October 2011. At that time, the separate app was also removed from the iOS
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
. Siri supports a wide range of user commands, including performing phone actions, checking basic information, scheduling events and reminders, handling device settings, searching the Internet, navigating areas, finding information on entertainment, and is able to engage with iOS-integrated apps. With the release of
iOS 10 iOS 10 is the iOS version history, tenth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 9. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers Conf ...
in 2016, Apple opened up limited third-party access to Siri, including third-party messaging apps, as well as payments, ride-sharing, and Internet calling apps. With the release of
iOS 11 iOS 11 is the iOS version history, eleventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 10. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers C ...
, Apple updated Siri's voices for more clear, human voices, it now supports follow-up questions and language translation, and additional third-party actions.


Game Center

Game Center is an
online In computer technology and telecommunications, online indicates a state of connectivity and offline indicates a disconnected state. In modern terminology, this usually refers to an Internet connection, but (especially when expressed "on line" or ...
multiplayer A multiplayer video game is a video game in which more than one person can play in the same game environment at the same time, either locally on the same computing system (couch co-op), on different computing systems via a local area network, or ...
"social gaming network" released by Apple. It allows users to "invite friends to play a game, start a multiplayer game through matchmaking, track their
achievements Achievement may refer to: *Achievement (heraldry) *Achievement (horse), a racehorse *Achievement (video gaming), a meta-goal defined outside of a game's parameters See also * Achievement test for student assessment * Achiever, a personality typ ...
, and compare their high scores on a leaderboard." iOS 5 and above adds support for profile photos. Game Center was announced during an iOS 4 preview event hosted by Apple on April 8, 2010. A preview was released to registered Apple developers in August. It was released on September 8, 2010, with iOS 4.1 on
iPhone 4 The iPhone 4 is a smartphone that was designed and marketed by Apple Inc. It is the fourth generation of the iPhone lineup, succeeding the iPhone 3GS and preceding the 4S. Following a number of notable leaks, the iPhone 4 was first unvei ...
, iPhone 3GS, and iPod Touch 2nd generation through 4th generation. Game Center made its public debut on the iPad with iOS 4.2.1. There is no support for the
iPhone 3G The iPhone 3G (also known as iPhone 2) is a smartphone that was designed and marketed by Apple Inc.; it is the second generation of iPhone, successor to the original iPhone, and was introduced on June 9, 2008, at the WWDC 2008 at the Moscon ...
, original iPhone and the first-generation iPod Touch (the latter two devices did not have Game Center because they did not get iOS 4). However, Game Center is unofficially available on the iPhone 3G via a hack.


Hardware

The main hardware platform for iOS is the
ARM architecture ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
(the
ARMv7 ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
,
ARMv8-A ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
,
ARMv8.2-A AArch64 or ARM64 is the 64-bit extension of the ARM architecture family. It was first introduced with the Armv8-A architecture. Arm releases a new extension every year. ARMv8.x and ARMv9.x extensions and features Announced in October 2011, AR ...
,
ARMv8.3-A AArch64 or ARM64 is the 64-bit extension of the ARM architecture family. It was first introduced with the Armv8-A architecture. Arm releases a new extension every year. ARMv8.x and ARMv9.x extensions and features Announced in October 2011, AR ...
). iOS releases before
iOS 7 iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 o ...
can only be run on iOS devices with
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...
ARM processors (
ARMv6 ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
and
ARMv7-A ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
architectures). In 2013,
iOS 7 iOS 7 is the seventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 6. It was announced at the company's Worldwide Developers Conference on June 10, 2013, and was released on September 18 o ...
was released with full
64-bit In computer architecture, 64-bit Integer (computer science), integers, memory addresses, or other Data (computing), data units are those that are 64 bits wide. Also, 64-bit central processing unit, CPUs and arithmetic logic unit, ALUs are those ...
support (which includes a native 64-bit kernel, libraries, drivers as well as all built-in applications), after Apple announced that they were switching to 64-bit
ARMv8-A ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
processors with the introduction of the
Apple A7 The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was announced on September 10, 2013, and the iPad Air and iPad Mini 2, which were both announced on October 22, 2013. Apple states ...
chip. 64-bit support was also enforced for all apps in the
App Store An App Store (or app marketplace) is a type of digital distribution platform for computer software called applications, often in a mobile context. Apps provide a specific set of functions which, by definition, do not include the running of the co ...
; All new apps submitted to the App Store with a deadline of February 2015, and all app updates submitted to the App Store with a deadline of June 1, 2015.
iOS 11 iOS 11 is the iOS version history, eleventh major release of the iOS mobile operating system developed by Apple Inc., being the successor to iOS 10. It was announced at the company's Apple Worldwide Developers Conference, Worldwide Developers C ...
drops support for all iOS devices with 32-bit ARM processors as well as 32-bit applications, making iOS 64-bit only.


Supported locales

iOS has support for many locales.


Notes

# The iPod Touch at its launch supported English, French, German, Japanese, Dutch, Italian, Spanish, Portuguese, Danish, Finnish, Norwegian, Swedish, Korean, Simplified Chinese, Traditional Chinese, Russian, and Polish. However, most of these languages were not available in the iPhone until iPhone 2.0. # As of iOS 8, users can add more than one locale to use on the device. If one language is not supported, the next one is used instead. The language on the top of the list is the primary one. # While these regions are present in iOS 8, they fall back to the generic regions for the system language. This issue has been resolved in iOS 9 and later, when a default region is added. #* de-AT, de-CH: de #* en-CA, en-US: en #* es-ES: es #* es-419: es-MX #* fr-CH: fr # iOS 9 and above improved the locale handling process, now applying a default region to those that have multiple regions. The region is not displayed in the locale name if the region is the same as the country/region setting, or if only one region is added for a language. #* German: German (Germany) #* English: English (US) #* Spanish: Spanish (Spain) #* French: French (France) #* Italian: Italian (Italy) #* Dutch: Dutch (Netherlands) #* Portuguese: Portuguese (Brazil) #* Chinese, Traditional: Chinese, Traditional (Taiwan) # Dutch (Belgium) was previously shown as Flemish in iOS 9 before being fixed in iOS 10, to bring it more in line with other locales. # iOS 10 and macOS Sierra were the last versions in which new locales were added for the languages supported by iOS and macOS. #* English (US): United States, Canada #* English (UK): United Kingdom, Ireland, Singapore, South Africa #* English (Australia): Australia, New Zealand #* English (India): India #* Chinese, Simplified: China mainland #* Chinese, Traditional (Taiwan): Taiwan #* Chinese, Traditional (Hong Kong): Hong Kong, Macau #* Japanese: Japan #* Spanish (Spain): Spain #* Spanish (Latin America): Latin America, Argentina, Bolivia, Chile, Colombia, Costa Rica, Dominican Republic, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Uruguay, US, Venezuela #* French (France): France, Belgium, Switzerland #* French (Canada): Canada #* German: Germany, Austria, Switzerland #* Russian: Russia #* Portuguese (Brazil): Brazil #* Portuguese (Portugal): Portugal #* Italian: Italy, Switzerland #* Korean: South Korea #* Turkish: Turkey #* Dutch: Netherlands, Belgium #* Arabic: Saudi Arabia #* Thai: Thailand #* Swedish: Sweden #* Danish: Denmark #* Vietnamese: Vietnam #* Norwegian Bokmål: Norway #* Polish: Poland #* Finnish: Finland #* Indonesian: Indonesia #* Hebrew: Israel #* Greek: Greece #* Romanian: Romania #* Hungarian: Hungary #* Czech: Czech Republic #* Catalan: Spain #* Slovak: Slovakia #* Ukrainian: Ukraine #* Croatian: Croatia #* Malay: Malaysia #* Hindi: India # It is possible to add custom locales in the iOS Simulator by editing the AppleLanguages portion of the .GlobalPreferences.plist file for each simulator.


Development

The iOS SDK (
Software Development Kit A software development kit (SDK) is a collection of software development tools in one installable package. They facilitate the creation of applications by having a compiler, debugger and sometimes a software framework. They are normally specific to ...
) allows for the development of
mobile app A mobile application or app is a computer program or software application designed to run on a mobile device such as a phone, tablet, or watch. Mobile applications often stand in contrast to desktop applications which are designed to run on d ...
s on iOS. While originally developing iPhone prior to its unveiling in 2007, Apple's then-
CEO A chief executive officer (CEO), also known as a central executive officer (CEO), chief administrator officer (CAO) or just chief executive (CE), is one of a number of corporate executives charged with the management of an organization especially ...
Steve Jobs Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American entrepreneur, industrial designer, media proprietor, and investor. He was the co-founder, chairman, and CEO of Apple; the chairman and majority shareholder of Pixar; a ...
did not intend to let third-party developers build native apps for iOS, instead directing them to make
web application A web application (or web app) is application software that is accessed using a web browser. Web applications are delivered on the World Wide Web to users with an active network connection. History In earlier computing models like client-serve ...
s for the Safari web browser. However, backlash from developers prompted the company to reconsider, with Jobs announcing in October 2007 that Apple would have a software development kit available for developers by February 2008. The SDK was released on March 6, 2008. The SDK is a free download for users of Mac personal computers. It is not available for
Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for serv ...
PCs. The SDK contains sets giving developers access to various functions and services of iOS devices, such as hardware and software attributes. It also contains an iPhone
simulator A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the s ...
to mimic the look and feel of the device on the computer while developing. New versions of the SDK accompany new versions of iOS. In order to test applications, get technical support, and distribute apps through App Store, developers are required to subscribe to the Apple Developer Program. Combined with
Xcode Xcode is Apple's integrated development environment (IDE) for macOS, used to develop software for macOS, iOS, iPadOS, watchOS, and tvOS. It was initially released in late 2003; the latest stable release is version 14.2, released on December 13, ...
, the iOS SDK helps developers write iOS apps using officially supported programming languages, including
Swift Swift or SWIFT most commonly refers to: * SWIFT, an international organization facilitating transactions between banks ** SWIFT code * Swift (programming language) * Swift (bird), a family of birds It may also refer to: Organizations * SWIFT, ...
and
Objective-C Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXTS ...
. Other companies have also created tools that allow for the development of native iOS apps using their respective programming languages.


Update history & schedule

Apple An apple is an edible fruit produced by an apple tree (''Malus domestica''). Apple fruit tree, trees are agriculture, cultivated worldwide and are the most widely grown species in the genus ''Malus''. The tree originated in Central Asia, wh ...
provides major updates to the iOS operating system annually via
iTunes iTunes () is a software program that acts as a media player, media library, mobile device management utility, and the client app for the iTunes Store. Developed by Apple Inc., it is used to purchase, play, download, and organize digital mul ...
and, since iOS 5, also over-the-air. The device checks an XML-based PLIST file on mesu.apple.com for updates. Updates are delivered as unencrypted ZIP files. Updates are checked for regularly, and are downloaded and installed automatically if enabled. Otherwise, the user can install them manually or are prompted to allow automatic installation overnight if plugged in and connected to Wi-Fi. iPod Touch users originally had to pay for system software updates due to accounting rules that designated it not a "subscription device" like the iPhone or Apple TV, causing many iPod Touch owners not to update. In September 2009, a change in accounting rules won tentative approval, affecting Apple's earnings and stock price, and allowing iPod Touch updates to be delivered free of charge. Apple significantly extended the cycle of updates for iOS-supported devices over the years. The
iPhone (1st generation) The iPhone (retrospectively referred to unofficially as the iPhone 2G, iPhone 1 or original iPhone) is the first iPhone model and the first smartphone designed and marketed by Apple Inc. After years of rumors and speculation, it was official ...
and
iPhone 3G The iPhone 3G (also known as iPhone 2) is a smartphone that was designed and marketed by Apple Inc.; it is the second generation of iPhone, successor to the original iPhone, and was introduced on June 9, 2008, at the WWDC 2008 at the Moscon ...
only received two iOS updates, while later models had support for five, six, and seven years.


XNU kernel

The iOS kernel is the XNU kernel of Darwin. The original iPhone OS (1.0) up to iPhone OS 3.1.3 used Darwin 9.0.0d1. iOS 4 was based on Darwin 10. iOS 5 was based on Darwin 11. iOS 6 was based on Darwin 13. iOS 7 and iOS 8 are based on Darwin 14. iOS 9 is based on Darwin 15. iOS 10 is based on Darwin 16. iOS 11 is based on Darwin 17. iOS 12 is based on Darwin 18. iOS 13 is based on Darwin 19. iOS 14 is based on Darwin 20. iOS 15 is based on Darwin 21. iOS 16 is based on Darwin 22. In
iOS 6 iOS 6 is the sixth major release of the iOS mobile operating system developed by Apple Inc, being the successor to iOS 5. It was announced at the company's Worldwide Developers Conference on June 11, 2012, and was released on September 19, 2 ...
the kernel is subject to
ASLR Address space layout randomization (ASLR) is a computer security technique involved in preventing Exploit (computer security), exploitation of memory corruption Vulnerability (computing), vulnerabilities. In order to prevent an attacker from reli ...
, similar to that of
OS X Mountain Lion OS X Mountain Lion (version 10.8) is the ninth major release of macOS, Apple Inc.'s desktop and server operating system for Macintosh computers. OS X Mountain Lion was released on July 25, 2012, for purchase and download through Apple's Mac Ap ...
. This makes exploit possibilities more complex since it is not possible to know the location of kernel code. Apple has made the XNU kernel
open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use the source code, design documents, or content of the product. The open-source model is a decentralized sof ...
. The source is under a 3-clause BSD license for the original BSD parts, with parts added by Apple under the Apple Public Source License. The versions contained in iOS are not available; only the versions used in
macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
are available. iOS does not have kernel extensions (kexts) in the file system, even if they are actually present. The kernel cache can be decompressed to show the correct kernel, along with the kexts (all packed in the __PRELINK_TEXT section) and their plists (in the __PRELINK_INFO section). The kernel cache can also be directly decompressed (if decrypted) using third-party tools. With the advent of iOS 10 betas and default plain text kernelcaches, these tools can only be used after unpacking and applying lzssdec to unpack the kernel cache to its full size. The kextstat provided by the
Cydia Cydia is a graphical user interface of APT (Advanced Package Tool) for iOS. It enables a user to find and install software not authorized by Apple on jailbroken iPhones, iPads and iPod Touch devices. It also refers to digital distribution pla ...
alternative software does not work on iOS because the kextstat is based on kmod_get_info(...), which is a deprecated API in
iOS 4 iOS 4 is the fourth major release of the iOS mobile operating system developed by Apple Inc., being the successor to iPhone OS 3. It was announced at the Apple Special Event on April 8, 2010, and was released on June 21, 2010. iOS 4 is the fi ...
and
Mac OS X Snow Leopard Mac OS X Snow Leopard (version 10.6) is the seventh major release of macOS, Apple's desktop and server operating system for Macintosh computers. Snow Leopard was publicly unveiled on June 8, 2009 at Apple’s Worldwide Developers Conference. ...
. There are other alternative software that can also dump raw XML data. On developing devices, the kernel is always stored as a statically linked cache stored in /System/Library/Caches/com.apple.kernelcaches/kernelcache which is unpacked and executed at boot. In the beginning, iOS had a kernel version usually higher than the corresponding version of
macOS macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...
. Over time, the kernels of iOS and macOS have gotten closer. This is not surprising, considering that iOS introduced new features (such as the ASLR Kernel, the default freezer, and various security-strengthening features) that were first incorporated and subsequently arrived on macOS. It appears Apple is gradually merging the iOS and macOS kernels over time. The build date for each version varies slightly between processors. This is due to the fact that the builds are sequential.


Kernel Image

The kernel image base is randomized by the boot loader (
iBoot iBoot is the stage 2 bootloader for all Apple products. It replaces the old bootloader, BootX. Compared with its predecessor, iBoot improves authentication performed in the boot chain. For x86 macOS, the boot process starts by running code stor ...
). This is done by creating random data, doing a SHA-1 hash of it and then using a byte from the SHA-1 hash for the kernel slide. The slide is calculated with this formula: base=0x01000000+(slide_byte*0x00200000) If the slide is 0, the static offset of 0x21000000 is used instead. The adjusted base is passed to the kernel in the boot arguments structure at offset 0x04, which is equivalent to gBootArgs->virtBase.


Kernel Map

The kernel map is used for kernel allocations of all types (kalloc(), kernel_memory_allocate(), etc.) and spans all of kernel space (0x80000000-0xFFFEFFFF). The kernel based maps are submaps of the kernel_map, for example zone_map, ipc_kernel_map, etc. The strategy is to randomize the base of the kernel_map. A random 9-bit value is generated right after kmem_init() which establishes kernel_map, is multiplied by the page size. The resulting value is used as the size for the initial kernel_map allocation. Future kernel_map (and submap) allocations are pushed forward by a random amount. The allocation is silently removed after the first garbage collection and reused. This behaviour can be overridden with the "kmapoff" boot parameter.


Attacks

Kext_request() allows applications to request information about kernel modules, divided into active and passive operations. Active operations (load, unload, start, stop, etc.) require root access. iOS removes the ability to load kernel extensions. Passive operations were originally (before
iOS 6 iOS 6 is the sixth major release of the iOS mobile operating system developed by Apple Inc, being the successor to iOS 5. It was announced at the company's Worldwide Developers Conference on June 11, 2012, and was released on September 19, 2 ...
) unrestricted and allowed unprivileged users to query kernel module base addresses. iOS6 inadvertently removed some limitations; only the load address requests are disallowed. So attackers can use kKextRequestPredicateGetLoaded to get load addresses and mach-o header dumps. The load address and mach-o segment headers are obscured to hide the ASLR slide, but mach-o section headers are not. This reveals the virtual addresses of loaded kernel sections. This information leak has been closed with iOS 6.0.1.


Versions codenames

Internally, iOS identifies each version by a codename, often used internally only, normally to maintain secrecy of the project. For example, the codename for
iOS 14 iOS 14 is the fourteenth major release of the iOS mobile operating system developed by Apple Inc. for their iPhone and iPod Touch lines. Announced at the company's Worldwide Developers Conference on June 22, 2020 as the successor to iOS 13 ...
is ''Azul.''


Jailbreaking

Since its initial release, iOS has been subject to a variety of different hacks centered around adding functionality not allowed by Apple. Prior to the 2008 debut of Apple's native
iOS App Store The App Store is an app store platform, developed and maintained by Apple Inc., for mobile apps on its iOS and iPadOS operating systems. The store allows users to browse and download approved apps developed within Apple's iOS Software Deve ...
, the primary motive for jailbreaking was to bypass Apple's purchase mechanism for installing the App Store's native applications. Apple claimed that it would not release iOS software updates designed specifically to break these tools (other than applications that perform SIM unlocking); however, with each subsequent iOS update, previously un-patched jailbreak exploits are usually patched. When a device is booting, it loads Apple's own
kernel Kernel may refer to: Computing * Kernel (operating system), the central component of most operating systems * Kernel (image processing), a matrix used for image convolution * Compute kernel, in GPGPU programming * Kernel method, in machine learnin ...
initially, so a jailbroken device must be exploited and have the kernel patched each time it is booted up. There are different types of jailbreak. An ''untethered'' jailbreak uses exploits that are powerful enough to allow the user to turn their device off and back on at will, with the device starting up completely, and the kernel will be patched without the help of a computer – in other words, it will be jailbroken even after each reboot. However, some jailbreaks are
tethered A tether is a cord, fixture, or flexible attachment that characteristically anchors something movable to something fixed; it also maybe used to connect two movable objects, such as an item being towed by its tow. Applications for tethers includ ...
. A tethered jailbreak is only able to temporarily jailbreak the device during a single boot. If the user turns the device off and then boots it back up without the help of a jailbreak tool, the device will no longer be running a patched kernel, and it may get stuck in a partially started state, such as Recovery Mode. In order for the device to start completely and with a patched kernel, it must be "re-jailbroken" with a computer (using the "boot tethered" feature of a tool) each time it is turned on. All changes to the files on the device (such as installed package files or edited system files) will persist between reboots, including changes that can only function if the device is jailbroken (such as installed package files). In more recent years, two other solutions have been created – ''semi-tethered'' and ''semi-untethered''. A semi-tethered solution is one where the device is able to start up on its own, but it will no longer have a patched kernel, and therefore will not be able to run modified code. It will, however, still be usable for normal functions, just like stock iOS. To start with a patched kernel, the user must start the device with the help of the jailbreak tool. A semi-untethered jailbreak gives the ability to start the device on its own. On first boot, the device will not be running a patched kernel. However, rather than having to run a tool from a computer to apply the kernel patches, the user is able to re-jailbreak their device with the help of an app (usually sideloaded using
Cydia Cydia is a graphical user interface of APT (Advanced Package Tool) for iOS. It enables a user to find and install software not authorized by Apple on jailbroken iPhones, iPads and iPod Touch devices. It also refers to digital distribution pla ...
Impactor) running on their device. In the case of the iOS 9.2-9.3.3 and 64-bit 10.x jailbreaks, Safari-based exploits were available, thereby meaning websites could be used to rejailbreak. In more detail: Each iOS device has a bootchain that tries to make sure only trusted/signed code is loaded. A device with a tethered jailbreak is able to boot up with the help of a jailbreaking tool because the tool executes exploits via USB that bypass parts of that "chain of trust", bootstrapping to a
pwned Leet (or "1337"), also known as eleet or leetspeak, is a system of modified spellings used primarily on the Internet. It often uses character replacements in ways that play on the similarity of their glyphs via reflection (mathematics), reflec ...
(no signature check
iBSSiBEC
or
iBoot iBoot is the stage 2 bootloader for all Apple products. It replaces the old bootloader, BootX. Compared with its predecessor, iBoot improves authentication performed in the boot chain. For x86 macOS, the boot process starts by running code stor ...
to finish the boot process. Since the arrival of Apple's native iOS App Store, and—along with it—third-party applications, the general motives for jailbreaking have changed. People jailbreak for many different reasons, including gaining filesystem access, installing custom device themes, and modifying SpringBoard. An additional motivation is that it may enable the installation of pirated apps. On some devices, jailbreaking also makes it possible to install alternative operating systems, such as Android and the Linux kernel. Primarily, users jailbreak their devices because of the limitations of iOS. Depending on the method used, the effects of jailbreaking may be permanent or temporary. In 2010, the
Electronic Frontier Foundation The Electronic Frontier Foundation (EFF) is an international non-profit digital rights group based in San Francisco, California. The foundation was formed on 10 July 1990 by John Gilmore, John Perry Barlow and Mitch Kapor to promote Internet ci ...
(EFF) successfully convinced the U.S. Copyright Office to allow an exemption to the general prohibition on circumvention of copyright protection systems under the
Digital Millennium Copyright Act The Digital Millennium Copyright Act (DMCA) is a 1998 United States copyright law that implements two 1996 treaties of the World Intellectual Property Organization (WIPO). It criminalizes production and dissemination of technology, devices, or s ...
(DMCA). The exemption allows jailbreaking of iPhones for the sole purpose of allowing legally obtained applications to be added to the iPhone. The exemption does not affect the contractual relations between Apple and an iPhone owner, for example, jailbreaking voiding the iPhone warranty; however, it is solely based on Apple's discretion on whether they will fix jailbroken devices in the event that they need to be repaired. At the same time, the Copyright Office exempted unlocking an iPhone from DMCA's anticircumvention prohibitions. Unlocking an iPhone allows the iPhone to be used with any wireless carrier using the same GSM or CDMA technology for which the particular phone model was designed to operate.


Unlocking

Initially most wireless carriers in the US did not allow iPhone owners to unlock it for use with other carriers. However AT&T allowed iPhone owners who had satisfied contract requirements to unlock their iPhone. Instructions to unlock the device are available from Apple, but it is ultimately at the sole discretion of the carrier to authorize unlocking the device. This allows the use of a carrier-sourced iPhone on other networks. Modern versions of iOS and the iPhone fully support LTE across multiple carriers wherever the phone was purchased. Programs to remove SIM lock restrictions are available, but are not supported by Apple, and most often not a permanent unlock – a soft unlock, which modifies the iPhone so that the baseband will accept the SIM card of any GSM carrier. SIM unlocking is not jailbreaking, but a jailbreak is also required for these unofficial software unlocks. The legality of software unlocking varies in each country; for example, in the US, there is a DMCA exemption for unofficial software unlocking of devices purchased before January 26, 2013.


Digital rights management

The closed and proprietary nature of iOS has garnered criticism, particularly by
digital rights Digital rights are those human rights and legal rights that allow individuals to access, use, create, and publish digital media or to access and use computers, other electronic devices, and telecommunications networks. The concept is particular ...
advocates such as the
Electronic Frontier Foundation The Electronic Frontier Foundation (EFF) is an international non-profit digital rights group based in San Francisco, California. The foundation was formed on 10 July 1990 by John Gilmore, John Perry Barlow and Mitch Kapor to promote Internet ci ...
, computer engineer and activist
Brewster Kahle Brewster Lurton Kahle ( ; born October 21, 1960)Alexa Internet profile
, via juggle.com. accessed Novemb ...
, Internet-law specialist
Jonathan Zittrain Jonathan L. Zittrain (born December 24, 1969) is an American professor of Internet law and the George Bemis Professor of International Law at Harvard Law School. He is also a professor at the Harvard Kennedy School, a professor of computer scie ...
, and the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)#501(c)(3), 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed ...
who protested the iPad's introductory event and have targeted the iPad with their "
Defective by Design Defective by Design (DBD) is an anti-DRM initiative by the Free Software Foundation. Digital rights management (DRM) technology restricts users' ability to freely use their purchased movies, music, literature, software, and hardware in ways the ...
" campaign. Competitor
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washing ...
, via a PR spokesman, criticized Apple's control over its platform. At issue are restrictions imposed by the design of iOS, namely
digital rights management Digital rights management (DRM) is the management of legal access to digital content. Various tools or technological protection measures (TPM) such as access control technologies can restrict the use of proprietary hardware and copyrighted works. ...
(DRM) intended to lock purchased media to Apple's platform, the development model (requiring a yearly subscription to distribute apps developed for the iOS), the centralized approval process for apps, as well as Apple's general control and lockdown of the platform itself. Particularly at issue is the ability for Apple to remotely disable or delete apps at will. Some in the tech community have expressed concern that the locked-down iOS represents a growing trend in Apple's approach to computing, particularly Apple's shift away from machines that hobbyists can "tinker with" and note the potential for such restrictions to stifle software innovation. Former
Facebook Facebook is an online social media and social networking service owned by American company Meta Platforms. Founded in 2004 by Mark Zuckerberg with fellow Harvard College students and roommates Eduardo Saverin, Andrew McCollum, Dustin M ...
developer Joe Hewitt protested against Apple's control over its hardware as a "horrible precedent" but praised iOS's sandboxing of apps.


Security and privacy

iOS utilizes many security features in both hardware and software. Below are summaries of the most prominent features.


Secure Boot

Before fully booting into iOS, there is low-level code that runs from the Boot
ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...
. Its task is to verify that the Low-Level
Bootloader A bootloader, also spelled as boot loader or called boot manager and bootstrap loader, is a computer program that is responsible for booting a computer. When a computer is turned off, its softwareincluding operating systems, application code, an ...
is signed by the Apple
Root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
CA public
key Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (map ...
before running it. This process is to ensure that no malicious or otherwise unauthorized software can be run on an iOS device. After the Low-Level Bootloader finishes its tasks, it runs the higher level bootloader, known as
iBoot iBoot is the stage 2 bootloader for all Apple products. It replaces the old bootloader, BootX. Compared with its predecessor, iBoot improves authentication performed in the boot chain. For x86 macOS, the boot process starts by running code stor ...
. If all goes well, iBoot will then proceed to load the iOS kernel as well as the rest of the operating system.


Secure Enclave

The Secure Enclave is a
coprocessor A coprocessor is a computer processor used to supplement the functions of the primary processor (the CPU). Operations performed by the coprocessor may be floating-point arithmetic, graphics, signal processing, string processing, cryptography o ...
found in iOS devices part of the A7 and newer chips used for data protection,
Touch ID Touch ID is an electronic fingerprint recognition feature designed and released by Apple Inc. that allows users to unlock devices, make purchases in the various Apple digital media stores (iTunes Store, App Store, and Apple Books Store), and aut ...
and
Face ID Face ID is a facial recognition system designed and developed by Apple Inc. for the iPhone and iPad Pro. The system allows biometric authentication for unlocking a device, making payments, accessing sensitive data, providing detailed facial ex ...
. The purpose of the Secure Enclave is to handle keys and other info such as biometrics that is sensitive enough to not be handled by the Application Processor (AP). It is isolated with a hardware filter so the AP cannot access it. It shares RAM with the AP, but its portion of the RAM (known as TZ0) is encrypted. The secure enclave itself is a flashable 4 MB AKF processor core called the secure enclave processor (SEP) as documented i
Apple Patent Application 20130308838
The technology used is similar t
ARM's TrustZone/SecurCore
but contains proprietary code for Apple KF cores in general and SEP specifically. It is also responsible for generating the UID key on A9 or newer chips that protects user data at rest. It has its own secure boot process to ensure that it is completely secure. A hardware
random number generator Random number generation is a process by which, often by means of a random number generator (RNG), a sequence of numbers or symbols that cannot be reasonably predicted better than by random chance is generated. This means that the particular out ...
is also included as a part of this coprocessor. Each device's Secure Enclave has a unique ID that is given to it when it is made and cannot be changed. This identifier is used to create a temporary key that
encrypts In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can deci ...
the
memory Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
in this portion of the system. The Secure Enclave also contains an anti-replay counter to prevent brute force attacks. The SEP is located in the devicetree under IODeviceTree:/arm-io/sep and managed by the AppleSEPManager driver. In 2020, security flaws in the SEP were discovered, causing concerns about Apple devices such as iPhones.


Face ID

Face ID is a face scanner that is embedded in the notch on iPhone models X, XS, XS Max, XR, 11, 11 Pro, 11 Pro Max, 12, 12 Mini, 12 Pro, 12 Pro Max, 13, 13 Mini, 13 Pro, 13 Pro Max, 14, and the 14 Plus. On the
iPhone 14 Pro The iPhone 14 Pro and iPhone 14 Pro Max are smartphones designed, developed, and marketed by Apple Inc. They are the sixteenth-generation flagship iPhones, succeeding the iPhone 13 Pro and iPhone 13 Pro Max. The devices were unveiled alongs ...
and the 14 Pro Max, it is embedded in the Dynamic Island. It can be used to unlock the device, make purchases, and log into applications among other functions. When used, Face ID only temporarily stores the face data in encrypted memory in the Secure Enclave, as described above. There is no way for the device's main processor or any other part of the system to access the raw data that is obtained from the Face ID sensor.


Passcode

iOS devices can have a passcode that is used to unlock the device, make changes to system settings, and encrypt the device's contents. Until recently, these were typically four numerical digits long. However, since unlocking the devices with a fingerprint by using Touch ID has become more widespread, six-digit passcodes are now the default on iOS with the option to switch back to four or use an alphanumeric passcode.


Touch ID

Touch ID is a fingerprint scanner that is embedded in the home button and can be used to unlock the device, make purchases, and log into applications among other functions. When used, Touch ID only temporarily stores the fingerprint data in encrypted memory in the Secure Enclave, as described above. Like Face ID, there is no way for the device's main processor or any other part of the system to access the raw fingerprint data that is obtained from the Touch ID sensor.


Address Space Layout Randomization

Address Space Layout Randomization (ASLR) is a low-level technique of preventing
memory corruption Memory corruption occurs in a computer program when the contents of a memory location are modified due to programmatic behavior that exceeds the intention of the original programmer or program/language constructs; this is termed as violation of ...
attacks such as
buffer overflow In information security and programming, a buffer overflow, or buffer overrun, is an anomaly whereby a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations. Buffers are areas of memory ...
s. It involves placing data in randomly selected locations in memory in order to make it more difficult to predict ways to corrupt the system and create exploits. ASLR makes app bugs more likely to crash the app than to silently overwrite memory, regardless of whether the behavior is accidental or malicious.


Non-executable memory

iOS utilizes the
ARM architecture ARM (stylised in lowercase as arm, formerly an acronym for Advanced RISC Machines and originally Acorn RISC Machine) is a family of reduced instruction set computer (RISC) instruction set architectures for computer processors, configured ...
's Execute Never (XN) feature. This allows some portions of the memory to be marked as non-executable, working alongside ASLR to prevent buffer overflow attacks including
return-to-libc attack A "return-to-libc" attack is a computer security attack usually starting with a buffer overflow in which a subroutine return address on a call stack is replaced by an address of a subroutine that is already present in the process executable memory ...
s.


Encryption

As mentioned above, one use of encryption in iOS is in the memory of th
Secure Enclave
When a passcode is utilized on an iOS device, the contents of the device are encrypted. This is done by using a hardware AES 256 implementation that is very efficient because it is placed directly between the
flash storage Flash memory is an electronic non-volatile computer memory storage medium that can be electrically erased and reprogrammed. The two main types of flash memory, NOR flash and NAND flash, are named for the NOR and NAND logic gates. Both use ...
and RAM. iOS, in combination with its specific hardware, uses
crypto-shredding Crypto-shredding is the practice of 'deleting' data by deliberately deleting or overwriting the encryption keys. This requires that the data have been encrypted. Data may be considered to exist in three states: data at rest, data in transit an ...
when erasing all content and settings by obliterating all the keys in ' effaceable storage'. This renders all user data on the device cryptographically inaccessible.


Keychain

The iOS keychain is a
database In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases sp ...
of login information that can be shared across apps written by the same person or organization. This service is often used for storing passwords for web applications.


App security

Third-party applications such as those distributed through the App Store must be code signed with an Apple-issued certificate. In principle, this continues the
chain of trust In computer security, a chain of trust is established by validating each component of hardware and software from the end entity up to the root certificate. It is intended to ensure that only trusted software and hardware can be used while still ...
all the way from the Secure Boot process as mentioned above to the actions of the applications installed on the device by users. Applications are also
sandboxed In computer security, a sandbox is a security mechanism for separating running programs, usually in an effort to mitigate system failures and/or software Vulnerability (computing), vulnerabilities from spreading. The isolation metaphor is taken ...
, meaning that they can only modify the data within their individual
home directory A home directory is a file system directory on a multi-user operating system containing files for a given user of the system. The specifics of the home directory (such as its name and location) are defined by the operating system involved; for ...
unless explicitly given permission to do otherwise. For example, they cannot access data owned by other user-installed applications on the device. There is a very extensive set of privacy controls contained within iOS with options to control apps' ability to access a wide variety of permissions such as the camera, contacts, background app refresh, cellular data, and access to other data and services. Most of the code in iOS, including third-party applications, runs as the "mobile" user which does not have root privileges. This ensures that system files and other iOS system resources remain hidden and inaccessible to user-installed applications.


App Store bypasses

Companies can apply to Apple for enterprise developer certificates. These can be used to sign apps such that iOS will install them directly (sometimes called "sideloading"), without the app needing to be distributed via the App Store. The terms under which they are granted make clear that they are only to be used for companies who wish to distribute apps directly to their employees. Circa January–February 2019, it emerged that a number of software developers were misusing enterprise developer certificates to distribute software directly to non-employees, thereby bypassing the App Store. Facebook was found to be abusing an Apple enterprise developer certificate to distribute an application to underage users that would give Facebook access to all
private data Information privacy is the relationship between the collection and dissemination of data, technology, the public expectation of privacy, contextual information norms, and the legal and political issues surrounding them. It is also known as data pr ...
on their devices. Google was abusing an Apple enterprise developer certificate to distribute an app to adults to collect data from their devices, including unencrypted data belonging to third parties. TutuApp, Panda Helper,
AppValley AppValley is an independent American digital distribution service operated and trademarked by AppValley LLC. It serves as an alternative app store for the iOS mobile operating system, which allows users to download applications that are not availab ...
, and TweakBox have all been abusing enterprise developer certificates to distribute apps that offer
pirated software Copyright infringement (at times referred to as piracy) is the use of works protected by copyright without permission for a usage where such permission is required, thereby infringing certain exclusive rights granted to the copyright holder, su ...
.


Network security

iOS supports TLS with both low- and high-level APIs for developers. By default, the App Transport Security framework requires that servers use at least TLS 1.2. However, developers are free to override this framework and utilize their own methods of communicating over networks. When Wi-Fi is enabled, iOS uses a randomized
MAC address A media access control address (MAC address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking techno ...
so that devices cannot be tracked by anyone sniffing wireless traffic.


Two-factor authentication

Two-factor authentication is an option in iOS to ensure that even if an unauthorized person knows an
Apple ID Apple ID is an authentication method used by Apple for iPhone, iPad, Mac and other Apple devices. Apple IDs contain the user's personal information and settings. When an Apple ID is used to log in to an Apple device, the device will automatica ...
and password combination, they cannot gain access to the account. It works by requiring not only the Apple ID and password, but also a verification code that is sent to an
iDevice Apple Inc. has developed four Unix-like operating systems, namely iOS, iPadOS, tvOS, and watchOS. Devices using these systems include the iPhone, iPod Touch, and iPad, which are mobile devices; the Apple TV, which is a digital media playe ...
or mobile phone number that is already known to be trusted. If an unauthorized user attempts to sign in using another user's Apple ID, the owner of the Apple ID receives a notification that allows them to deny access to the unrecognized device.


Hardened memory allocation

iOS features a hardened memory allocator known as kalloc_type that was introduced in iOS 15. Since the XNU kernel is primarily written in memory unsafe languages such as C and
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
, kalloc_type is designed to mitigate the large amount of
vulnerabilities Vulnerability refers to "the quality or state of being exposed to the possibility of being attacked or harmed, either physically or emotionally." A window of vulnerability (WOV) is a time frame within which defensive measures are diminished, com ...
that result from the use of these languages in the kernel. In order to achieve this, kalloc_type implements mitigations such as type isolation in order to prevent type confusion and
buffer overflow In information security and programming, a buffer overflow, or buffer overrun, is an anomaly whereby a program, while writing data to a buffer, overruns the buffer's boundary and overwrites adjacent memory locations. Buffers are areas of memory ...
vulnerabilities. Ultimately, the prevention of
privilege escalation Privilege escalation is the act of exploiting a bug, a design flaw, or a configuration oversight in an operating system or software application to gain elevated access to resources that are normally protected from an application or user. The res ...
is intended.


Reception


Market share

iOS is the second most popular mobile operating system in the world, after Android. Sales of iPads in recent years are also behind Android, while, by web use (a proxy for all use), iPads (using iOS) are still the most popular. By the middle of 2012, there were 410 million devices activated. At
WWDC The Worldwide Developers Conference (WWDC) is an information technology conference held annually by Apple Inc. The conference is usually held at Apple Park in California. The event is usually used to showcase new software and technologies in t ...
2014,
Tim Cook Timothy Donald Cook (born November 1, 1960) is an American business executive who has been the chief executive officer of Apple Inc. since 2011. Cook previously served as the company's chief operating officer under its co-founder Steve Jobs. ...
said 800 million devices had been sold by June 2014. During Apple's quarterly earnings call in January 2015, the company announced that they had sold over one billion iOS devices since 2007. By late 2011, iOS accounted for 60% of the market share for smartphones and tablets. By the end of 2014, iOS accounted for 14.8% of the smartphone market and 27.6% of the tablet and two-in-one market. In February 2015,
StatCounter StatCounter is a web traffic analysis website started in 1999. Access to basic services is free to use and advanced services can cost between and US$119 a month. StatCounter is based in Dublin, Ireland. The statistics from StatCounter are used ...
reported iOS was used on 23.18% of smartphones and 66.25% of tablets worldwide, measured by internet usage instead of sales. In the third quarter of 2015, research from Strategy Analytics showed that iOS adoption of the worldwide smartphone market was at a record low 12.1%, attributed to lackluster performance in China and Africa. Android accounted for 87.5% of the market, with Windows Phone and BlackBerry accounting for the rest.


Devices


See also

*
Comparison of mobile operating systems This is a comparison of mobile operating systems. Only the latest versions are shown in the table below, even though older versions may still be marketed. About OS Advanced controls Accessibility features App ecosystem Browser ...
*
Android (operating system) Android is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of de ...
* *


References


Further reading

* * * *


External links

* * Dev Center at
Apple Developer Connection Apple Developer (formerly Apple Developer Connection) is Apple Inc.'s website for software development tools, application programming interfaces (APIs), and technical resources. It contains resources to help software developers write software for ...

iOS Reference Library
– on the Apple Developer Connection website {{Authority control Apple Inc. operating systems Mach (kernel) Mobile operating systems Products introduced in 2007 Smartphones Tablet operating systems