What I did to play a custom sound was I just did Add File "Glass Drum.caf" to add it to the Bundle, then in the func where I schedule the alarm in the AlarmConfiguration I add sound: AlertConfiguration.AlertSound.named("Glass Drum.caf") and that works.
Also be sure you have imported ActivityKit.
My problem is that when I hit the Stop button, the alarm is dismissed, but the sound keeps playing.
I also have the problem where if I haven't locked the screen I get the sound but no alarm visual presentation.
Any help on those items would be great.