This is very weird, that should be some law requiring them to provide such list. As an app provider, how would I know otherwise that somebody bought the app or not?

Thanks a lot for the response. Does this architecture "retry" a notification if it cannot deliver the message in the first try?

Local Notifications were also ones I thought of. However, the way I understand, Local Notifications are permission based. User must grant the necessary permission. This is not the case in Apple's Stopwatch or in Alarm or in Timer. It is a competitive disadvantage. How can I build a customized timer the way Apple implements? I don't see any functionality within the iOS SDK.