Access network services and handle changes in network configurations. Build on abstractions of network protocols to simplify tasks such as working with BSD sockets, administering HTTP and FTP servers, and managing Bonjour services.

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 Foundation framework provides a base layer of functionality for apps and frameworks, including data storage and persistence, text processing, date and time calculations, sorting and filtering, and networking. The classes, protocols, and data types defined by Foundation are used throughout the macOS, iOS, watchOS, and tvOS SDKs.

macOS Launch Services is an API that enables a running app to open other apps or their document files, similar to the Finder or the Dock.Launch Services eliminates apps having to query the Finder to open an app, document, or URL for them. The macOS Finder itself uses Launch Services to perform such tasks. Because the Finder performs no additional processing beyond calling Launch Services, any client using Launch Services for these purposes behaves identically to the Finder.

The Message UI framework provides specialized view controllers for presenting standard composition interfaces for email and SMS (Short Messaging Service) text messages. Use these interfaces to add message delivery capabilities without requiring the user to leave your app.

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.

Allow users to browse, edit, and save images, using slideshows and Core Image filters.The Quartz Composer API supports processing and rendering graphical data and allows developers to create custom patches for the Quartz Composer developer tool. ImageKit provides user interface support for browsing, editing, and saving images, showing slideshows, and browsing and previewing Core Image filters. PDFKit is a technology that allows applications to display and manipulate PDF documents.

Secure the data your app manages. Protect information and control access to your app.

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.