title: added button to sceneKit view but it has a lag
body: <p>I added a custom button to the sceneKit view. When it is touched, it plays an animation, indicating that it was clicked. The problem I'm facing is the delay between user touch and start of animation. My scene has 28.1K triangles and 84.4K vertices. Is that to much or do I need to implement buttons differently. The scene renders with 60fps. I added the button via <strong>sceneView.addSubview:</strong> Thanks for answers</p>
  
  <pre><code>     viewDidLoad(){
       // relevant code
          starButton = UIButton(type: UIButtonType.Custom)
          starButton.frame = CGRectMake(100, 100, 50, 50)
          starButton.setImage(UIImage(named: "yellowstar.png"), forState: UIControlState.Normal)
          sceneView.addSubview(starButton)
          starButton.addTarget(self, action: "starButtonClicked", forControlEvents: UIControlEvents.TouchUpInside)
          starButton.adjustsImageWhenHighlighted = false
          }
  
  
  
      func starButtonClicked(){
              animateScaleDown()
  
          }
  
      func animateScaleDown(){
  
          UIView.animateWithDuration(0.1, animations: {
              self.starButton.transform = CGAffineTransformMakeScale(0.8, 0.8)
  
              }, completion: { _ in
                  self.wait()
          })
  
      }
  
      func wait(){
          UIView.animateWithDuration(0.2, animations: {}, completion: { _ in
              UIView.animateWithDuration(0.2, animations: {
                  self.starButton.transform = CGAffineTransformMakeScale(1, 1)
  
              })
          })
      }
  </code></pre>