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 fourth-generation Apple TV, from Apple Inc.
Cocoa Touch provides an abstraction layer of iOS, the operating system for the iPhone, iPod Touch, and iPad. Cocoa Touch is based on the macOS Cocoa API toolset and, like it, is primarily written in the Objective-C language. Cocoa Touch allows the use of hardware and features that are not found in macOS computers and are thus unique to the iOS range of devices. Just like Cocoa, Cocoa Touch follows a Model-View-Controller (MVC) software architecture.
iOS, watchOS, and tvOS technologies can be seen as a set of layers, with Cocoa Touch at the highest level and the Core OS/kernel at the bottom.
A hierarchical view of the iOS, watchOS, and tvOS technologies can be shown as follows:
Some of the main features and technologies of Cocoa Touch are:
Cocoa Touch provides the key frameworks for developing applications on devices running iOS. Some of these key frameworks are:
Microsoft's WinObjC, the GNUstep-based iOS bridge for the Universal Windows Platform, contains a working implementation of Cocoa Touch frameworks like Foundation, UIKit, and MapKit released under the MIT License. One of the UIKit implementations is based on XAML.
Various efforts have tried to bring UIKit, the modified AppKit from Cocoa Touch, to macOS: