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What is SwiftUI?

Developer terms Published

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SwiftUI is Apple’s framework for declaring an app’s user interface and behaviour across its platforms. You describe what the screen should show for a given state, and SwiftUI draws it and keeps it up to date. Apple lists it as available on macOS from 10.15.

Why it matters

SwiftUI means less code for each screen and the same views across Apple platforms. For a Mac app, it is usually combined with AppKit, the older framework for windows and system integration, because some jobs still need AppKit.

How NotchStar uses it

NotchStar is a native Mac app in Swift using SwiftUI and AppKit. Views such as the tool tabs are SwiftUI. The notch window is an AppKit NSPanel that hosts them.

One practical limit came up while recording demo clips. An AppKit control, ProgressView, did not redraw in offscreen captures: the time text updated but the bar did not. The fix was a small SwiftUI ThinBar and Spinner, in ToolStyle.swift. It is a reminder that a control which looks the same on screen can behave differently when you draw it somewhere unusual.

Read what is a notch app for the product side. Live gauges such as the System tool are plain SwiftUI views over data sampled once a second.

Keep reading.

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.
What is 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 a notch app? A plain English guide
A notch app turns the dead space around the MacBook notch into a tiny control center. Here is how they work, what they do and what to watch for.
CPU, memory, disk, battery and network
Live CPU, memory, disk, battery and network speed gauges in your Mac notch. Sampling only runs while the tab is open, so it stays light.

More in Developer terms.

What is 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 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.
What is 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?
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?
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?
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.
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