Question

I’d like my app to have different functionality depending on whether it launched while it was still active in the background (i.e. not fully exited) versus when it gets relaunched after a phone call. Possible?

Answers I found on stackoverflow were mostly related to how to resume after a phone call at all.

EDIT: I found an answer to this question on apple forums dated 2008 which involved making deductions based on the duration of your average phone call, looks like that is still the most valid option?

Answer 1

In your appdelegate there are two methods which will becalled in your app is running and a for example a phone call comes in:

- (void)applicationWillResignActive:(UIApplication *)application {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

And is called when you app becomes active again.

- (void)applicationDidBecomeActive:(UIApplication *)application {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

There is sure NO way to tell if a phone is has been made if you app was in background or not running when the call started.