Update a UI from Background thread when app is also in Background to show Splash Screen on next resume

Question

I want to show a Splash screen when app remain in background for more than 3 minutes. I started Background timer to trigger the function that will handle the UI update.

- (void)applicationDidEnterBackground:(UIApplication *)
if (application.applicationState == UIApplicationStateBackground) {
    UIBackgroundTaskIdentifier bgTask = UIBackgroundTaskInvalid;
    UIApplication *app = [UIApplication sharedApplication];
    bgTask = [app beginBackgroundTaskWithExpirationHandler:^{
        [app endBackgroundTask:bgTask];
    }];
    //and create new timer with async call:
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
        splashTimer = [NSTimer scheduledTimerWithTimeInterval:5 target:self selector:@selector(timerFired) userInfo:nil repeats:NO];
        [[NSRunLoop currentRunLoop] addTimer:splashTimer forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] run];
    });
}
}

Now when the timer is invoked i call the function to update my UI i.e adding an image in the window so make it look like that it is a Splash Screen.

  - (void)timerFired
    {
      [splashTimer invalidate];
        [[NSOperationQueue mainQueue] addOperationWithBlock:^{
            UIImageView *splash = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Splash_Screen.png"]];
            splash.frame = self.window.bounds;
            [self.window addSubview:splash];
        }];
}

and then remove This image from the window when Application Enter foreground again

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    if ([[self.window subviews] count] > 1) {
        [NSThread sleepForTimeInterval:1.0];
        [[[self.window subviews] lastObject] removeFromSuperview];
    }
}

but my Splash Screen is not shown when i call it from a background thread. I tried everything but no luck. My Problem is that My Timer is being invoked from a Background thread and if i want to add image from this thread the UI is not updated. Any Help?

Answer 1

Springboard does not update your app's snapshot[1] when all background tasks have expire/ended. IIRC when your application is in the background, the snapshot is only updated just before your app is suspended after handling these background events:

• Background Fetch/Refresh
• Remote Notification
• (I don't recall the third one. Background Download maybe?)

[1] The image that appears in the task switcher and while your application is being moved back to the foreground.