The Address Book framework provides access to a centralized contacts database, called the Address Book database, that stores a user’s contacts. Applications such as Mail and Messages use this database to present information about known and unknown persons.

The CloudKit framework provides interfaces for moving data between your app and your iCloud containers.You use CloudKit to take your app’s existing data and store it in the cloud so that the user can access it on multiple devices. You can also store data in a public area where all users can access it.

The Contacts framework provides Swift and Objective-C API to access the user’s contact information. Because most apps read contact information without making any changes, this framework is optimized for thread-safe, read-only usage.

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.

The GLKit framework provides functions and classes that reduce the effort required to create new shader-based apps or to port existing apps that rely on fixed-function vertex or fragment processing provided by earlier versions of OpenGL ES or OpenGL.

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.