Need help identifying app state during phone call in iOS 14? - ios

Question

I have an app that does a certain task.
While performing this task, the app also listens for when the user receives a phone call.
If the user receives a phone call, this task needs to be interrupted.
On iOS 13 we listen to willResignActiveNotification for when the incoming call and to didBecomeActiveNotification for when the call ends (this for when the user has the app open before the phone call).
On iOS 14 this also works if the call setting is set to Full Screen.
But when this setting is changed to Banner these notifications are never triggered.
I can't identify the app state for when the setting is set to Banner. My guess is that it is still in the active state.
The problem is that although the notifications are not called, the UI is interrupted as if the app was placed in the background when the user has the Banner setting on.
Note
I also conform to CXCallObserverDelegate and implement callObserver(_ callObserver: CXCallObserver, callChanged call: CXCall) method to know when the user receives a call and when the call ends.
So a solution is to just resume the task when the call ends and this method is triggered.
But I want to understand the app lifecycle in this case which is not making sense to me.
Code Sample
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
NotificationCenter.default.addObserver(self, selector: #selector(appDidEnterBackground(_:)), name: UIApplication.didEnterBackgroundNotification, object: nil)
NotificationCenter.default.addObserver(self, selector: #selector(appWillEnterForeground(_:)), name: UIApplication.willEnterForegroundNotification, object: nil)
timer.resume()
updateUI()
}
override func viewWillDisappear(_ animated: Bool) {
timer.invalidate()
pauseUI()
NotificationCenter.default.removeObserver(self, name: UIApplication.didEnterBackgroundNotification, object: nil)
NotificationCenter.default.removeObserver(self, name: UIApplication.willEnterForegroundNotification, object: nil)
super.viewWillDisappear(animated)
}
#objc private func appDidEnterBackground(_ notification: Notification) {
timer.invalidate()
pauseUI()
}
#objc private func appWillEnterForeground(_ notification: Notification) {
timer.resume()
updateUI()
}

Answer 1

Since iOS 10 our app uses callObserver:callChanged: from CXCallObserverDelegate to detect incoming or answered phone calls like:
#import CallKit;
#property (nonatomic) CXCallObserver *callObserver;
#pragma mark - Application lifecycle
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Register Call Observer to detect incoming calls:
_callObserver = [[CXCallObserver alloc] init];
[_callObserver setDelegate:self
queue:nil];
}
#pragma mark - CXCallObserverDelegate
- (void)callObserver:(CXCallObserver *)callObserver callChanged:(CXCall *)call {
// Based on state:
if (call.hasEnded) {
NSLog(#"CXCallObserver: Call has ended");
}
else if (call.hasConnected) {
NSLog(#"CXCallObserver: Call has connected");
}
else if (!call.isOutgoing && !call.hasConnected && !call.hasEnded) {
NSLog(#"CXCallObserver: Call is incoming");
}
else {
NSLog(#"CXCallObserver: None of the conditions");
}
}
Since the default behaviour on iOS 14 is to show a banner for incoming calls, we indeed saw that CXCallObserverDelegate was not called anymore.
When we changed the Phone setting in the iOS app to Full Screen it did work again. Obviously, just like in iOS 13 and before.
However, when we flipped the setting back to Banner, our app did call CXCallObserverDelegate event on an incoming banner call.
Based on the numerous issues with Local Network permission in iOS 14, it's only an estimated guess that here a similar root cause applies, where settings are only handed over to the native functionality once actively set by the user, and not on a default system setting.
I hope that explicitly changing the setting will solve your issue, or that we were accidentally lucky.
Note: the observations are done on iPhone SE 2nd gen with iOS 14.6.