title: cornerRadius of UIImageView not working
body: <p>I had set cornerRadius like below:</p>
  
  <pre><code>@IBDesignable class CornerImageView: UIImageView {
  @IBInspectable var cornerRadiusValue: CGFloat = 10.0 {
      didSet {
          setUpView()
      }
  }
  override func awakeFromNib() {
      super.awakeFromNib()
      setUpView()
  }
  override func prepareForInterfaceBuilder() {
      super.prepareForInterfaceBuilder()
      setUpView()
  }
  
  func setUpView() {
      self.layer.cornerRadius = self.cornerRadiusValue == -1 ? self.bounds.size.height/2 : self.cornerRadiusValue
      self.clipsToBounds = true
  }
  }
  </code></pre>
  
  <p>On storyboard, it worked correctly. But failed when run on device.
  Please help!!!</p>
  
  <p><a href="https://i.stack.imgur.com/swfFM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/swfFM.png" alt="wrong cornerRadius"></a></p>
  
  <p><a href="https://i.stack.imgur.com/S7vtU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/S7vtU.png" alt="on Storyboard"></a></p>