AppKit (formally Application Kit) is a graphical user interface toolkit. It initially served as the UI framework for NeXTSTEP. Along with Foundation and Display PostScript, it became one of the core parts of the OpenStep specification of APIs. Later, AppKit and Foundation became part of

Cocoa Cocoa may refer to: Chocolate * Chocolate * ''Theobroma cacao'', the cocoa tree * Cocoa bean, seed of ''Theobroma cacao'' * Chocolate liquor, or cocoa liquor, pure, liquid chocolate extracted from the cocoa bean, including both cocoa butter and ...

, the Objective-C API framework of macOS. GNUstep, GNU's implementation of the OpenStep/Cocoa API, also contains an implementation of the AppKit API. AppKit comprises a collection of Objective-C classes and protocols that can be used to build an application in OpenStep/Cocoa. These classes can also be used in Swift through its Objective-C bridge. Xcode has built-in functionality for developing a Cocoa application using AppKit, including the ability to visually design user interfaces with Interface Builder. It relies heavily on patterns like

reference types In computer programming, data types can be divided into two categories: value types (or by-value types) and reference types (or by-reference types). Value types are completely represented by their meaning, while reference types are references to a ...

delegation Delegation is the assignment of authority to another person (normally from a manager to a subordinate) to carry out specific activities. It is the process of distributing and entrusting work to another person,Schermerhorn, J., Davidson, P., Poole ...

notifications Notification may refer to: * Notification (Holy See), an announcement by a department of the Roman Curia *Casualty notification, the process of notifying relatives of people who have been killed or seriously injured * Death notification, the proc ...

target–action The term target–action design paradigm refers to a kind of software architecture, where a computer program is divided into objects which dynamically establish relationships by telling each other which object they should target and what action o ...

, and

model–view–controller Model–view–controller (MVC) is a software architectural pattern commonly used for developing user interfaces that divide the related program logic into three interconnected elements. This is done to separate internal representations of infor ...

. A sign of the NeXTSTEP heritage, AppKit's classes and protocols still use the "NS" prefix. Most of the applications bundled with macOS—for example, the

Finder Finder may refer to: * Finder (surname) * Finder (software), part of the Apple Macintosh operating system * ''Finder'' (comics), a comic book series by Carla Speed McNeil * ''Finder'' (novel), a 1994 novel by Emma Bull * Finder Wyvernspur, a fi ...

, TextEdit,

Calendar A calendar is a system of organizing days. This is done by giving names to periods of time, typically days, weeks, months and years. A date is the designation of a single and specific day within such a system. A calendar is also a physi ...

, and Preview–use AppKit to provide their user interface. macOS, iOS, iPadOS, and tvOS also support other UI frameworks, including UIKit, which is derived from AppKit and uses many similar structures, and SwiftUI, a Swift-only declarative UI framework. Prior to macOS Catalina, macOS also supported Carbon, a UI framework derived from the Macintosh Toolbox.

Classes

Of the more than 170 classes included in the Application Kit, the following classes form the core:AppKit Framework Reference
/ref> *NSApplication: a singleton object that represents the application as a whole and tracks its windows and other global state *NSWindow: an object representing a window on screen, it holds a hierarchy of views *NSView: an object representing a rectangular region; it may draw UI content of its own (using drawing engines like Quartz, Core Animation, and Metal), and it may also hold a subtree of other views *NSResponder: an object that can respond to events during the application's lifetime; NSApplication, NSWindow, and NSView are all subclasses of NSResponder *NSDocument: an object representing a document saved on disk that manages its display in a window *NSController: an abstract class implementing some functionality for a controller, mediating between views and model objects

References

{{reflist

External links

AppKit classes, in OpenStep specification

Apple developer documentation for AppKit
NeXT MacOS Application programming interfaces

Classes

See also

References

External links