title: I didn't get any notifications when I touched on tabbar items
body: <p>I have UITabbarCoo=ntroller application. I added an observer and I'm waiting for any notifications. I didn't get any notifications when I touched on tabbar items.</p>
  
  <pre><code>[self.tabBarController addObserver:self forKeyPath:@"selectedIndex" options:NSKeyValueObservingOptionNew context:@"changedTabbarIndex"];
  
   - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
  {
   NSString *action = (NSString*)context; 
   if([action isEqualToString:@"changedTabbarIndex"])
       {
       }
   }
  </code></pre>