On the MusicKit page it says This library prompts the user to sign in to Apple Music and, if Apple Music isn’t installed on the device, helps the user download it before returning to your app. Does this mean it plays the music through the Apple Music app so it will work offline if the songs have been downloaded in the Apple Music app? I would test this myself, but it's insane that I have to pay $142 AUD for a developer account just to see if it works! Absolutely insane. Hopefully someone else can test it for me.