title: How to subscribe self on the event of Device Orientation(not interface orientation)?
body: <p>in my app i want to call some method in CCScene myscene in the case of device rotation(orientation change).I disabled the autorotation(because i want it not to happen).</p>
  
  <p>The issue is: i want to change gravity in the scene depending on my device orientation.
  My code :</p>
  
  <pre><code>-(void) onEnter
  {
      [super onEnter];
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(notification_OrientationWillChange:) name:UIApplicationWillChangeStatusBarOrientationNotification object:nil];
      [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(notification_OrientationDidChange:) name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
  }
  -(void) onExit
  {
      //[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillChangeStatusBarOrientationNotification object:nil];
      //[[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidChangeStatusBarOrientationNotification object:nil];
  }
  -(void)notification_OrientationWillChange:(NSNotification*)n
  {
      orientation = (UIInterfaceOrientation)[[n.userInfo objectForKey:UIApplicationStatusBarOrientationUserInfoKey] intValue];
  }
  -(void)notification_OrientationDidChange:(NSNotification*)n
  {
      if (orientation == UIInterfaceOrientationLandscapeLeft) {
          b2Vec2 gravity( 0, -10);
          world-&gt;SetGravity(gravity);
      }
      if (orientation == UIInterfaceOrientationLandscapeRight) {
          b2Vec2 gravity( 0, 10);
          world-&gt;SetGravity(gravity);
      }
  }
  </code></pre>
  
  <p>But in this case i can get notifications only in the case of autorotation enabled.(if it disabled, device is actually don't change it status bar orientation)
  Can you help me?</p>