Developers

Aerial has shipped as a .saver plug-in, as an app-extension screensaver, and now as a wallpaper extension. This section collects what that work taught, as sample code and notes for developers building their own macOS screensavers.

Screensaver extensions

Since macOS 10.15 (2019), the screensavers that ship with the system started moving from being .saver plug-ins to app extensions. To date, Apple has not published that extension point for third-party developers. This series documents the AppexSaverMinimal sample project through observations made from the system’s own bundles. It has only been tested on macOS 14 up to macOS 27.

Build a screensaver as an app extension Package a macOS screensaver as an app extension hosted by a regular app, provide its view through the ScreenSaver framework's extension classes, and share rendering code with an in-app preview.

Understand the screensaver extension lifecycle Learn which processes host an app-extension screensaver, how one instance serves every display and outlives its views, and what the extension receives when the screensaver starts and ends.

Add a configuration sheet and persist settings Present an Options sheet from System Settings, end it the way the framework expects, and store settings that both instances of the extension read.

Register, install and distribute the screensaver Register a development build with pluginkit, avoid duplicate registrations, provide a thumbnail, choose entitlements, and notarize the app that carries the screensaver.