title: how to do imageView.startAnimating() with completion in swift?
body: <p>I would like a simple image array animation to run when a button is clicked. The below code works well, but I would like the last image in the array to be set as the imageview image after. How would I change the image on completion instead of it going back to the original?</p>
  
  <pre><code>let imageArray = [UIImage(named: "Frog-1.gif")!, UIImage(named: "Frog-2.gif")!, UIImage(named: "Frog-3.gif")!, UIImage(named: "Frog-4.gif")!]
  
  @IBOutlet var imageView1: UIImageView!
  
  @IBAction func button1(sender: UIButton) {
  
      imageView1.animationImages = imageArray
      imageView1.animationDuration = 1.0
      imageView1.animationRepeatCount = 1
      imageView1.startAnimating()
  
  }
  </code></pre>