title: When pinching in UIScrollView the image just jumps down and left and then the whole ScrollView freezes
body: <p>So i have a scrollView and an image view inside and everything works great(scrolling) until i try to pinch to zoom when the whole picture just jumps to the down and left and stays the same size but when i lift my finger the scrollView just freezes, even the scrolling stops working. Here is the code:</p>
  
  <pre><code>class ScrollViewViewController: ViewController, UIScrollViewDelegate {
  
  @IBOutlet weak var scrollView: UIScrollView!
  
  var imageView = UIImageView()
  var image = UIImage() {
      didSet {imageView.image = image}
  }
  
  override func viewDidLoad() {
      super.viewDidLoad()
  
      let imageView = UIImageView(image: image)
      imageView.frame = CGRect(origin: CGPointZero, size: image.size)
      scrollView?.addSubview(imageView)
      scrollView?.contentSize = imageView.frame.size
      scrollView?.delegate = self
      scrollView?.minimumZoomScale = 0.5
      scrollView?.maximumZoomScale = 2
  }
  
  func viewForZoomingInScrollView(scrollView: UIScrollView) -&gt; UIView? {
      return imageView
  }
  }
  </code></pre>
  
  <p>Anyone sees any potential problems?</p>