A simple macOS menu bar icon to change the system theme, made with Swift
Version 1.0 - download from the GitHub Release
Alternatively, you can clone this repo and compile the app yourself. The 'App' folder and project contains the app that sits on your menu bar and the 'Helper' folder contains the required helper tool. The helper tool must be installed to ~/.DarkLight with the same name unless you change the main app code. You will also need to add the .plist to /Library/LaunchAgents for the app to install automatically when you log in. Or....you could just download and run the .pkg and have all of this done for you :)
I'd like to distrubute this app through the Mac App Store, however part of how this application works is blocked by the Mac App Store.