title: Changing an Autolayout-constrained UIView's frame at runtime in Swift
body: <p>For example, I use this code to change the frame position of a <code>UIView</code> called <code>Propo</code>:</p>
  
  <pre><code>        self.Propo.frame.origin.x -= self.view.frame.width
  </code></pre>
  
  <p>(<code>Propo</code> has constraints in Storyboard)</p>
  
  <p>But When the app view disappears and reappears, the <code>UIView</code> resets itself to its original position. How can I do to resolve it? I want the <code>UIView</code> to keep its position when I change it programmatically.</p>
  
  <p>I've tried <code>updateViewConstraints()</code> by anything else append...</p>