# What is AppKit?

> AppKit is Apple's older framework for building Mac apps with windows, menus and events. Learn what it covers and why SwiftUI apps still use it.

Canonical: https://www.notchstar.com/glossary/appkit/
Last updated: 2026-11-04

Published 2026-11-04.

AppKit is Apple's framework for constructing and managing a graphical, event driven user interface for a macOS app. It has been on the Mac since macOS 10.0. Windows, menus, the pasteboard, drag and drop and screens all come from AppKit.

## Why it matters

[SwiftUI](https://www.notchstar.com/glossary/swiftui/) is newer, but it does not cover every Mac behaviour. When an app needs control over a window's level or whether it takes keyboard focus, it falls back to AppKit. Most real Mac apps use both.

## What NotchStar takes from AppKit

- The notch window, an [NSPanel](https://www.notchstar.com/glossary/nspanel/).
- The clipboard, read through [NSPasteboard](https://www.notchstar.com/glossary/nspasteboard/).
- The screen geometry, including the [safe area](https://www.notchstar.com/glossary/safe-area/) inset that locates the notch.
- Dragging screenshots out of the tray, which uses an AppKit dragging source and not SwiftUI's drag, so that copy, move and delete behave as they do in Finder.
- Sharing to AirDrop, through the system sharing service.

## Limits

AppKit is Mac only. A cross platform app cannot reuse it on other systems, which is one reason a Windows version of NotchStar would be a separate app and not a port.

## Related

Read [what is a notch app](https://www.notchstar.com/guides/what-is-a-notch-app/) for the user side and the [Screenshot Tray](https://www.notchstar.com/features/screenshot-tray/) for the drag behaviour.

## Keep reading.

- [What is SwiftUI?](https://www.notchstar.com/glossary/swiftui/): SwiftUI is Apple's framework for declaring an app's user interface in Swift code. Learn what it does, how it meets AppKit and how NotchStar uses both.
- [What is NSPanel?](https://www.notchstar.com/glossary/nspanel/): NSPanel is the AppKit window class for auxiliary windows such as palettes and utility panels. Learn why a notch app uses a non activating one.
- [What is NSPasteboard?](https://www.notchstar.com/glossary/nspasteboard/): NSPasteboard is the AppKit object that moves data to and from the Mac clipboard. Learn how apps read it and why clipboard managers poll change count.
- [What is the safe area on a Mac screen?](https://www.notchstar.com/glossary/safe-area/): The safe area is the part of a screen where content is not covered by hardware such as the notch. Developers read it from NSScreen safeAreaInsets in AppKit.

## More in Developer terms.

- [What is NSPanel?](https://www.notchstar.com/glossary/nspanel/): NSPanel is the AppKit window class for auxiliary windows such as palettes and utility panels. Learn why a notch app uses a non activating one.
- [What is SwiftUI?](https://www.notchstar.com/glossary/swiftui/): SwiftUI is Apple's framework for declaring an app's user interface in Swift code. Learn what it does, how it meets AppKit and how NotchStar uses both.
- [What is NSPasteboard?](https://www.notchstar.com/glossary/nspasteboard/): NSPasteboard is the AppKit object that moves data to and from the Mac clipboard. Learn how apps read it and why clipboard managers poll change count.
- [What is MediaRemote on macOS?](https://www.notchstar.com/glossary/mediaremote/): MediaRemote is a private Apple framework that reports what is playing on a Mac. Learn why it is restricted since macOS 15.4 and how notch apps work around it.
- [What is hover intent?](https://www.notchstar.com/glossary/hover-intent/): Hover intent is a short delay before a hover opens something, so passing the pointer by does not trigger it. Learn how NotchStar tunes it at the notch.
- [What does open source mean?](https://www.notchstar.com/glossary/open-source/): Open source software publishes its source code under a license that lets others read and change it. Learn the definition and how it differs from closed source.