AppKit
AppKit is a macOS framework that provides the user interface and application infrastructure for building native macOS applications. It includes classes for windows, views, controls, menus, and event handling, enabling developers to create desktop apps with a consistent macOS look and feel. It is part of Apple's Cocoa framework and is written in Objective-C and Swift.
Developers should learn AppKit when building native desktop applications for macOS, as it offers direct access to macOS-specific features like the menu bar, dock integration, and system services. It is essential for creating professional-grade apps that adhere to Apple's Human Interface Guidelines, such as productivity tools, creative software, or utilities that require deep system integration.