Detect incoming calls on iPhone?

I have a custom bluetooth module that connects to an iPhone and I want to make it vibrate when there is an incoming call. I can detect the call state when the my app is in the foreground but I want to detect calls when the app is suspended and the phone is locked.


I know this is possible since the iWatch does it, but is it possible for a mere mortal like me (or do I need special OS access)?


PS: I have practically no Objective C or Swift coding experience.


Thanks in Advance!