title: Intercepting pan gestures over a UIScrollView breaks scrolling
body: <p>I have a vertically-scrolling <code>UIScrollView</code>. I want to also handle horizontal pans on it, while allowing the default vertical scroll behavior. I've put a transparent <code>UIView</code> over the scroll view, and added a pan gesture recognizer to it. This way I can get the pans just fine, but then the scroll view doesn't receive any gestures.</p>
  
  <p>I've implemented the following <code>UIPanGestureRecognizerDelegate</code> methods, hoping to limit my gesture recognizer to horizontal pans only, but that didn't help:</p>
  
  <pre><code>- (BOOL)gestureRecognizerShouldBegin:(UIPanGestureRecognizer *)gestureRecognizer {
      // Only accept horizontal pans here.
      // Leave the vertical pans for scrolling the content.
      CGPoint translation = [gestureRecognizer translationInView:self.view];
      BOOL isHorizontalPan = (fabsf(translation.x) &gt; fabsf(translation.y));
      return  isHorizontalPan;
  }
  
  - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
      return (otherGestureRecognizer == _scrollView.panGestureRecognizer);
  }
  </code></pre>