The iOS SDK (iOS Software Development Kit), formerly the iPhone SDK, is 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 t ...

(SDK) developed by

Apple Inc. Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Comput ...

The kit 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 smartphone, phone, tablet computer, tablet, or smartwatch, watch. Mobile applications often stand in contrast to desktop appli ...

s on Apple's

iOS Ios, Io or Nio (, ; ; locally Nios, Νιός) is a Greek island in the Cyclades group in the Aegean Sea. Ios is a hilly island with cliffs down to the sea on most sides. It is situated halfway between Naxos and Santorini. It is about long an ...

and

iPadOS iPadOS is a mobile operating system developed by Apple for its iPad line of tablet computers. It was given a name distinct from iOS, the operating system used by Apple's iPhones to reflect the diverging features of the two product lines, suc ...

operating systems. The iOS SDK is a free download for users of

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

(or Mac) personal computers. It is not available for

Microsoft Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

PCs. The SDK contains sets giving developers access to various functions and services of iOS devices, such as hardware and

software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

attributes. It also contains an iPhone

simulator A simulation is an imitative representation of a process or system that could exist in the real world. In this broad sense, simulation can often be used interchangeably with model. Sometimes a clear distinction between the two terms is made, in ...

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 An app store, also called an app marketplace or app catalog, 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 i ...

, developers are required to subscribe to the Apple Developer Program. Combined with

Xcode Xcode is a suite of developer tools for building apps on Apple devices. It includes an integrated development environment (IDE) of the same name for macOS, used to develop software for macOS, iOS, iPadOS, watchOS, tvOS, and visionOS. It w ...

, the iOS SDK helps developers write iOS apps using officially supported

programming language A programming language is a system of notation for writing computer programs. Programming languages are described in terms of their Syntax (programming languages), syntax (form) and semantics (computer science), semantics (meaning), usually def ...

s, 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 * SWIF ...

and

Objective-C Objective-C is a high-level general-purpose, object-oriented programming language that adds Smalltalk-style message passing (messaging) to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was ...

. Other companies have also created tools that allow for the development of native iOS apps using their respective programming languages.

History

While originally developing

iPhone The iPhone is a line of smartphones developed and marketed by Apple that run iOS, the company's own mobile operating system. The first-generation iPhone was announced by then–Apple CEO and co-founder Steve Jobs on January 9, 2007, at ...

prior to its unveiling in 2007, Apple's then-

CEO A chief executive officer (CEO), also known as a chief executive or managing director, is the top-ranking corporate officer charged with the management of an organization, usually a company or a nonprofit organization. CEOs find roles in variou ...

Steve Jobs Steven Paul Jobs (February 24, 1955 – October 5, 2011) was an American businessman, inventor, and investor best known for co-founding the technology company Apple Inc. Jobs was also the founder of NeXT and chairman and majority shareholder o ...

did not intend to let third-party developers build native apps for the

operating system, instead directing them to make

web application A web application (or web app) is application software that is created with web technologies and runs via a web browser. Web applications emerged during the late 1990s and allowed for the server to dynamically build a response to the request, ...

s for the Safari web browser. However, backlash from developers prompted the company to reconsider, with Jobs announcing on October 17, 2007, that Apple would have a

(SDK) available for developers by February 2008. The SDK was released on March 6, 2008.

Features

The iOS SDK is a free download for Mac users. It is not available for

. To test the application, get technical support, and distribute applications through

, developers are required to subscribe to the Apple Developer Program. The SDK contents are separated into the following sets: *

UIKit UIKit is an application development environment and graphical user interface toolkit from Apple Inc. used to build apps for the iOS, iPadOS, watchOS, tvOS, and visionOS operating systems. UIKit provides an abstraction layer of iOS, the operati ...

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 CE ...

events and controls **

Accelerometer An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change (mathematics), rate of change of velocity) of the object relative to an observer who is in free fall (tha ...

support **View hierarchy ** Localization (i18n) **

Camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

support *

Media Media may refer to: Communication * Means of communication, tools and channels used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Interactive media, media that is inter ...

OpenAL OpenAL (Open Audio Library) is a cross-platform audio application programming interface (API). It is designed for efficient rendering of multichannel three-dimensional positional audio. Its API style and conventions deliberately resemble those o ...

audio mixing Audio mixing is the process by which multiple sounds are combined into one or more audio channels. In the process, a source's volume level, frequency content, dynamics, and panoramic position are manipulated or enhanced. This practical, aest ...

and recording **Video playback **

Image file format An image file format is a file format for a digital image. There are many formats that can be used, such as JPEG, PNG, and GIF. Most formats up until 2022 were for storing 2D images, not 3D ones. The data stored in an image file format may be co ...

s **

Quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

Core Animation Core Animation is an animation graphics compositing framework used by macOS (Mac OS X Leopard and later), iOS, watchOS, and tvOS to produce animated user interfaces. Overview Core Animation provides a way for developers to produce animated user ...

OpenGL ES OpenGL for Embedded Systems (OpenGL ES or GLES) is a subset of the OpenGL computer graphics rendering application programming interface (API) for rendering 2D and 3D computer graphics such as those used by video games, typically hardware-accelerate ...

* Core Services ** Networking **Embedded

SQLite SQLite ( "S-Q-L-ite", "sequel-ite") is a free and open-source relational database engine written in the C programming language. It is not a standalone app; rather, it is a library that software developers embed in their apps. As such, it ...

database **Core Location ** Threads **CoreMotion * Mac OS X Kernel **

TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...

** Sockets **

Power management Power management is a feature of some electrical appliances, especially copiers, computers, computer CPUs, computer GPUs and computer peripherals such as monitors and printers, that turns off the power or switches the system to a low-power ...

** File system **

Security Security is protection from, or resilience against, potential harm (or other unwanted coercion). Beneficiaries (technically referents) of security may be persons and social groups, objects and institutions, ecosystems, or any other entity or ...

The SDK also contains an iPhone simulator, a program used to simulate the look and feel of iPhone on the developer's computer. New SDK versions accompany new iOS versions.

Programming languages

The iOS SDK, combined with

, helps developers write iOS applications using officially supported programming languages, including

and

. An .ipa (iOS App Store Package) file is an iOS application archive file which stores an iOS app.

Java

In 2008,

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

announced plans to release a

Java Virtual Machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descr ...

(JVM) for iOS, based on the

Java Platform, Micro Edition Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top ...

version of Java. This would enable Java applications to run on iPhone and iPod Touch. Soon after the announcement, developers familiar with the SDK's terms of agreement believed that by not allowing third-party applications to run in the background (answer a phone call and still run the application, for example), and not allowing an application to download code from another source, nor allowing an application to interact with a third-party application, Sun's development efforts could be hindered without Apple's cooperation. Sun also worked with a third-party company called Innaworks in attempts to get Java on iPhone. Despite the apparent lack of interest from Apple, a

firmware In computing Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, h ...

leak of the 2007 iPhone release revealed an ARM chip with a processor with

Jazelle Jazelle DBX (direct bytecode execution) is an extension that allows some ARM processors to execute Java bytecode in hardware as a third execution state alongside the existing ARM and Thumb modes. Jazelle functionality was specified in the ARMv5TE ...

support for embedded Java execution.

.NET

Novell Novell, Inc. () was an American software and services company headquartered in Provo, Utah, that existed from 1980 until 2014. Its most significant product was the multi-platform network operating system known as NetWare. Novell technolog ...

announced in September 2009 that they had successfully developed MonoTouch, a

software framework In computer programming, a software framework is a software abstraction that provides generic functionality which developers can extend with custom code to create applications. It establishes a standard foundation for building and deploying soft ...

that let developers write native iPhone applications in the C# and

.NET The .NET platform (pronounced as "''dot net"'') is a free and open-source, managed code, managed computer software framework for Microsoft Windows, Windows, Linux, and macOS operating systems. The project is mainly developed by Microsoft emplo ...

programming languages, while still maintaining compatibility with Apple's requirements.

Flash

iOS does not support

Adobe Flash Adobe Flash (formerly Macromedia Flash and FutureSplash) is a mostly discontinuedAlthough it is discontinued by Adobe Inc., for the Chinese market it is developed by Zhongcheng and for the international enterprise market it is developed by Ha ...

, and although

Adobe Adobe (from arabic: الطوب Attub ; ) is a building material made from earth and organic materials. is Spanish for mudbrick. In some English-speaking regions of Spanish heritage, such as the Southwestern United States, the term is use ...

has two versions of its software: Flash and Flash Lite, Apple views neither as suitable for the iPhone, claiming that full Flash is "too slow to be useful", and Flash Lite to be "not capable of being used with the Web". In October 2009, Adobe announced that an upcoming update to its Creative Suite would feature a component to let developers build native iPhone apps using the company's Flash development tools. The software was officially released as part of the company's Creative Suite 5 collection of professional applications.

2010 policy on development tools

In April 2010, Apple made controversial changes to its iPhone Developer Agreement, requiring developers to use only "approved" programming languages in order to publish apps on

, and banning applications that used third-party development tools; the ban affected Adobe's Packager tool, which converted Flash apps into iOS apps. After developer backlash and news of a potential anti-trust investigation, Apple again revised its agreement in September, allowing the use of third-party development tools.

Mac Catalyst

Originally called "Project Marzipan", Mac Catalyst helps developers bring

app experiences to macOS, and make it easier to take apps developed for iPadOS devices to Macs by avoiding the need to write the underlying software code twice.

References

External links

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