title: Simultaneous gesture recognition for specific gestures
body: <p>I'm trying to enable simultaneous gesture recognition but only for the <code>UIPinchGestureRecognizer</code> and <code>UIRotationGestureRecognizer</code> gestures. I don't want it to work for any other gestures. If I set the following property to true it allows all gestures to be recognized simultaneously, how can I limit it to just rotating and scaling?</p>
  
  <pre><code>func gestureRecognizer(UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer: UIGestureRecognizer) -&gt; Bool {
      return true
  }
  </code></pre>