title: Stop animateWithDuration
body: <p>I have a cycle animate in <code>viewController</code></p>
  
  <pre><code>- (void)moveAnimating
  {
      [UIView animateWithDuration:2.0f animations:^{
          _backgroundView.center = CGPointMake(self.center.x , self.center.y - kMoveDistanceHeight);
       } completion:^(BOOL finished) {
          if (_backgroundView.animating)
          {
             [_backgroundView moveAnimating];
          }
      }];
  }
  </code></pre>
  
  <p>I want stop this animate When the <code>viewController</code> <code>viewWillDisappear</code>:</p>
  
  <pre><code>- (void)viewWillDisappear:(BOOL)animated
  {
      [super viewWillDisappear:animated];
      _backgroundView.animating = NO;
      [_backgroundView.layer removeAllAnimations];
  }
  </code></pre>
  
  <p>Because the animation is conflict with <code>dismissViewcontrollerAnimation</code>.</p>
  
  <p>Question:</p>
  
  <pre><code>[_backgroundView.layer removeAllAnimations];
  </code></pre>
  
  <p>not work...</p>
  
  <p>How to stop the animation？ </p>
  
  <p>Help me,thanks.</p>