Add notifications

[skjiisa]

It would be nice to be able to set a time to give a notification if a track isn't ticked that day.

Unfortunately, I don't know how to do this with iCloud sync. The app could set and update local notifications on launch, but if you tick a day on one device, I don't know how to make it so other devices delete their local notification.

This might be possible with CloudKit push notifications, but if it is, I don't know how.

[skjiisa]

From some testing, it seems like this is possible, but it might not be reliable if the app is closed (to be clear, it works when the app is in the background, but I'm not sure if it works after the app has been force closed).

By making a CKQuerySubscription to the CloudKit Core Data record and setting its shouldSendContentAvailable to true, we can add a UIApplicationDelegateAdaptor to App and use didReceiveRemoteNotification to get and process silent CloudKit notifications.

[skjiisa]

Notifications not syncing in the background might actually be fine. Looks like other apps like Due don't do this. The widget sync actually ended up working better than expected, so if we also update the notifications when the widget syncs, that could make the notification experience a lot better for users who use both notifications and the widget.

[skjiisa]

This could maybe be locked behind a premium feature.