This is the script I use to have my desktop background rotate through images submitted to /r/EarthPorn.

If you want to use it, you need a working Swift environment first.

1. Change the OutputDir path in Sources/Settings.swift

2. Build the script with swift build -c release

3. Use launchd to run the service.

• Edit dk.stjernegard.bgfetch.plist.example to your liking. Remember to change the Program path.
• mv dk.stjernegard.bgfetch.plist.example ~/Library/LaunchAgents/dk.stjernegard.bgfetch.plist
• launchctl load dk.stjernegard.bgfetch.plist

4. Use the OutputDir folder as source for your desktop background and let it autorotate as much as you want.