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.

This collection of documents describes the programming interfaces of the System Configuration framework. The System Configuration framework provides functions that determine the reachability of target hosts in both a synchronous and an asynchronous manner. It also provides error detection facilities.

The AV Foundation framework provides an Objective-C interface for managing and playing audio-visual media in iOS and OS X applications.

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 Location framework lets you determine the current location or heading associated with a device. The framework uses the available hardware to determine the user’s position and heading. You use the classes and protocols in this framework to configure and schedule the delivery of location and heading events. You can also use it to define geographic regions and monitor when the user crosses the boundaries of those regions. In iOS, you can also define a region around a Bluetooth beacon.

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.