ios animation not restarting - ios

Question

My UI uses animation of a UILabel to indicate a particular state. I turn that state on and off by using a key in NSUserDefaults standardUserDefaults. The animation restarts correctly (in the simulator) when the app becomes active after simulating the Home button and then clicking on the app. But it doesn't restart correctly if I simulate the Lock button and then click Home. Both events show in the console and the method -(void)startFlashingButton is called in both cases. I can't figure out why it works in one case and not in the other. I would appreciate any help.
Edit 2/14/17: I read several posts on other boards relating to UINotification. It is apparently very difficult to get to work. My animation gets triggered when a notification comes in to the app delegate. I wanted to set up a kind of "do not disturb" system that would silence notifications at a particular time. My understanding is that this cannot be automated by UINotification because the app does not see a notification unless it is front and center OR it is in the background and the user taps on one of the action buttons. If the app is in background and the user ignores the alert, the app will not get triggered and thus has no way of knowing if the do not disturb time has been reached. Also, you can't do this reliably with an NSTimer because the timer won't be recognized when the app is suspended, which it would be shortly after going to background. So, to put it briefly, I have a much bigger problem than the simulation not running. But thanks to all of you for your replies.
Here is the startFlashingButton method:
-(void) startFlashingButton
{
NSUserDefaults *storage = [NSUserDefaults standardUserDefaults];
if([storage boolForKey:#"animation started"] == YES){
// Fade out the view right away
[UIView animateWithDuration:2.0
delay: 0.0
options: (UIViewAnimationOptionCurveEaseIn | UIViewAnimationOptionRepeat | UIViewAnimationOptionAllowUserInteraction)
animations:^{
self.timerLabel.alpha = 0.0;
}
completion:^(BOOL finished){
// Wait one second and then fade in the view
[UIView animateWithDuration:1.0
delay: 2.0
options:UIViewAnimationOptionCurveEaseOut
animations:^{
self.timerLabel.alpha = 1.0;
}
completion:nil];
}];
}
[storage synchronize];
}
In -viewDidLoad, I set up the app to be notified when it becomes active as follows:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(startFlashingButton) name:UIApplicationDidBecomeActiveNotification object:nil];
In the app delegate, I synchonize the user defaults when the app enters background as follows:
- (void)applicationDidEnterBackground:(UIApplication *)application {
// Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
// If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
NSLog(#"application did enter background");
NSUserDefaults *storage = [NSUserDefaults standardUserDefaults];
[storage synchronize];

Answer 1

As Apple's documentation on background transition cycle states
When the user presses the Home button, presses the Sleep/Wake button, or the system launches another app, the foreground app transitions to the inactive state and then to the background state. These transitions result in calls to the app delegate’s applicationWillResignActive: and applicationDidEnterBackground: methods.
Hence The app might resign being active but not being in the background when you lock and then press the home button.
Try creating this helper method and call it in both applicationWillResignActive: and applicationDidEnterBackground:
-(void)saveUserDefaults {
NSLog(#"application did enter background");
NSUserDefaults *storage = [NSUserDefaults standardUserDefaults];
[storage synchronize];
}
Also, make sure that Application does not run in background in your info.plist is set to NO else your app will go to the suspended.