In iOS and OS X, the Photos framework (formerly known as Assets Library framework) provides classes that support building photo editing extensions for the Photos app. In iOS, the Photos framework also provides direct access to the photo and video assets managed by the Photos app, including the iCloud Photo Library. Use this framework to retrieve assets for display and playback, edit their image or video content, or work with collections of assets such as albums, moments, and iCloud Shared Albums.

Core Foundation is a framework that provides fundamental software services useful to application services, application environments, and to applications themselves. Core Foundation also provides abstractions for common data types, facilitates internationalization with Unicode string storage, and offers a suite of utilities such as plug-in support, XML property lists, URL resource access, and preferences.

The Core Graphics framework is based on the Quartz advanced drawing engine. It provides low-level, lightweight 2D rendering with unmatched output fidelity. You use this framework to handle path-based drawing, transformations, color management, offscreen rendering, patterns, gradients and shadings, image data management, image creation, and image masking, as well as PDF document creation, display, and parsing.

Core Text is an advanced, low-level technology for laying out text and handling fonts.

The Open Graphics Library (OpenGL) is used for visualizing 2D and 3D data. It is a multipurpose open-standard graphics library that supports applications for 2D and 3D digital content creation, mechanical and architectural design, virtual prototyping, flight simulation, video games, and more. You use OpenGL to configure a 3D graphics pipeline and submit data to it. Vertices are transformed and lit, assembled into primitives, and rasterized to create a 2D image. OpenGL is designed to translate function calls into graphics commands that can be sent to underlying graphics hardware. Because this underlying hardware is dedicated to processing graphics commands, OpenGL drawing is typically very fast.

This collection of documents provides the API reference for the Quartz Core framework, which supports image processing and video image manipulation.

The UIKit framework (UIKit.framework) provides the crucial infrastructure needed to construct and manage iOS apps. This framework provides the window and view architecture needed to manage an app’s user interface, the event handling infrastructure needed to respond to user input, and the app model needed to drive the main run loop and interact with the system.

Display web content in windows. Implement browser features such as following user-activated links, managing a back-forward list, and managing a history of recently visited pages. WebKit provides a set of classes to display web content in windows, and implements browser features such as following links when clicked by the user, managing a back-forward list, and managing a history of pages recently visited. WebKit greatly simplifies the complicated process of loading webpages—that is, asynchronously requesting web content from an HTTP server where the response may arrive incrementally, in random order, or partially due to network errors. WebKit also simplifies the process of displaying that content which can contain various MIME types, and compound frame elements each with their own set of scroll bars. WebCore is a framework developed by Apple, and licence under the LGPL, to provide an HTML layout engine for Mac OS X. It is one half of WebKit (the other being JavaScriptCore). WebCore combines the open source KHTML layout engine developed by the KDE project, with an adapter library called KWQ (pronounced Quack). Apple created the KWQ adapter to replace KHTML's dependency on code from the Qt toolkit and other KDE modules. KWQ also presents an Objective-C application programming interface to the C++-based KHTML rendering engine, allowing it to easily be referenced by Cocoa-based applications.