title: removeObserver not working for UIApplicationWillEnterForegroundNotification IOS
body: <p>Hi I am developing iPhone application in which I am registering for UIApplicationWillEnterForegroundNotification for notification. But when I tried to unregister that observer then its not working. It still get called. My code looks like </p>
  
  <p>in viewDidLoad method I am registering like this </p>
  
  <pre><code>  [[NSNotificationCenter defaultCenter]
   addObserver:self
   selector:@selector(applicationBecomeActive)
   name:UIApplicationWillEnterForegroundNotification
   object:nil];
  </code></pre>
  
  <p>And on my logout method I tried to remove this observer like this </p>
  
  <pre><code> [[NSNotificationCenter defaultCenter] removeObserver:UIApplicationWillEnterForegroundNotification];
  </code></pre>
  
  <p>but this is not working. Am I doing some thing wrong. Need some help. Thank you.</p>