PushKit Crash due to Late Processing

[ismailgulek]

Sometimes when we receive a VoIP push, we kill the app intentionally because app protected data is not available. Next time user opens the app and background the app, that VoIP push not processed is received in the PKPushRegistryDelegate. And this leads to an expired call invite for the iOS app and leaving us desperate about Apple's PushKit restrictions, which mandates us to report a new incoming call to the CallKit. In this case, OS terminates the app.

[ismailgulek]

Documentation of isProtectedDataAvailable says:

The value of this property is false if data protection is enabled and the device is currently locked. The value of this property is set to true if the device is unlocked or if content protection is not enabled.
When the value of this property is false, files that were assigned the _complete_ or _completeUnlessOpen_ protection key cannot be read or written by your app. The user must unlock the device before your app can access them.

So it wasn't a wise decision to terminate the app when the property is false, because we're not enabled an extra Data Protection for the app and iOS should be on completeUntilFirstUserAuthentication by default, which means we should be able to access data after first unlock of the device until another reboot. Also we're using the same level of protection for keychain items, so they should be accessible too. Also NSE could fetch the event and decrypt it, so we should be able to process app data at that time. It seems we can remove this check.