Cocoa Touch

Cocoa Touch

Developer(s)	Apple Inc.
Operating system	iOS
Type	Software framework
License	Proprietary
Website	developer.apple.com/technologies/ios/cocoa-touch.html

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.

Cocoa Touch contains a different set of graphical control elements from Cocoa. Tools for developing applications based on Cocoa Touch are included in the iOS SDK.

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:

1. Cocoa Touch
2. Media / Application Services
3. Core Services
4. Core OS / iOS kernel

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:

• Chameleon is a port of UIKit to macOS from 2014.
• ZeeZide's UXKit is a more recent port of UIKit to macOS. It exists a layer above AppKit and UIKit.
• Apple used a "UXKit" private framework for a 2015 version of Photos.app.
• Apple made the bridge more official with the "iosMac" or "Marzipan" project in 2018, which put an "iOSSupport" directory full of iOS frameworks in macOS Mojave. They were originally restricted from developer use and was finally made official with the release of Mac Catalyst in 2019.