title: Swift: Reset frame of a UIView to its constraints after animation
body: <p>I am setting a UIImageView using constraints added programmatically in <code>viewDidLoad</code>.</p>
  
  <p>Later on, after the user interacts with some buttons on the screen, I move the view by changing its frame using <code>CAKeyframeAnimation with an array of</code>CGRect` values for the movement.</p>
  
  <p>Now later in the app lifecycle, I'd like the <code>UIImageView</code> returned to where it was originally placed (using the constraints that I haven't changed). Is there a way to reset the frames to their initial constraints?</p>