Question

[[UIApplication sharedApplication] cancelAllLocalNotifications];
[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];'

I added the above code to didfinishLaunchingWithOptions but when a user taps a notification in his notification center and enters my app the notification does not gets cleared.

Edit:

I also tried adding this to my code:

You Also need to increment then decrement the badge in your
application:didReceiveRemoteNotification: method if you are trying
to clear the message from the message centre so that when a user
enters you app from pressing a notification the message centre will
also clear, ie:

[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 1];
[[UIApplication sharedApplication] setApplicationIconBadgeNumber: 0];
[[UIApplication sharedApplication] cancelAllLocalNotifications];  

as describes here: iOS application: how to clear notifications? but the notification still won’t clear from the notification center

Answer 1

I just Added a Badge number manually to my application and pasted

- (void)applicationDidBecomeActive:(UIApplication *)application
{
      application.applicationIconBadgeNumber = 0;
}

To my AppDelegate. For me this works like a charm.
Note that didfinishLaunchingWithOptions and applicationDidBecomeActive are not the same as Mouhammad Lamaa explained. If you paste this to your AppDelegate and tap the notification in notification center it should disapper. If it does not your App maybe creates a new Notification after becoming active?