[ajconway]

Apple removed the ability of app developers to use the (somewhat) reliable way to deliver events to apps without alerting the user.

There’s API that lets an app to decrypt visible notifications, but it’s incredibly limited (it will crash if the process uses more than 5 MB if RAM, if I remember correctly). This presents unique challenges as the app’s code also takes up RAM.

There’s also an old API that enables developers to silently wake up the app in background, but it’s highly unreliable (it won’t work more than 3-5 times per hour or so). This one can still be used for tracking.