title: Zoom not working in scroll view
body: <p>I have a scrollview in swift 3.  The zoom is not working.  I have set up the scrollview and put an imageview inside.  I have set self as the delegate and implemented viewForZoomingInScrollView.  please take a look.  thanks.</p>
  
  <p>edit:  another thing I didn't mention before was that this is view in a navigation controller.  would that affect it?</p>
  
  <pre><code>class FlowDiagramViewController: UIViewController, UIScrollViewDelegate {
  
      var scrollView: UIScrollView!
      var imageView:UIImageView! = UIImageView()
  
      override func viewDidLoad() {
          super.viewDidLoad()
  
          // Do any additional setup after loading the view.
          let image = UIImage(named: "flowNewRotated1242x2208.png")
          imageView = UIImageView(image: image)
  
          setupPictureWithZoom()
      }
  
      override func didReceiveMemoryWarning() {
          super.didReceiveMemoryWarning()
          // Dispose of any resources that can be recreated.
      }
  
      func setupPictureWithZoom() {
          // http://stackoverflow.com/questions/30014241/uiimageview-pinch-zoom-swift
  
          imageView.frame = CGRect(x: 0, y: 0, width: 1242, height: 2208)
          // imageView.transform = imageView.transform.rotated(by: CGFloat(M_PI_2))
          imageView!.layer.cornerRadius = 11.0
          imageView!.clipsToBounds = false
  
          scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height))
  
  
          scrollView.minimumZoomScale = 0.25
          scrollView.maximumZoomScale = 5.0
  
          scrollView.delegate = self
  
          scrollView.backgroundColor = UIColor(red: 90, green: 90, blue: 90, alpha: 0.90)
          scrollView.alwaysBounceVertical = false
          scrollView.alwaysBounceHorizontal = false
          scrollView.showsVerticalScrollIndicator = true
          scrollView.flashScrollIndicators()
          scrollView.contentSize = CGSize(width: 1242, height: 2208)
  
  
          scrollView.addSubview(imageView!)
          view.addSubview(scrollView!)
  
  
          scrollView.setZoomScale(0.25, animated: true)
      }
  
      func viewForZoomingInScrollView(scrollView: UIScrollView!) -&gt; UIView! {
          return imageView
      }
  }
  </code></pre>
  
  <p>I have tried both defining the scrollview in the storyboard and in code.  </p>