title: Xcode Swipe Gesture doesn't change constraint constant
body: <p>I have an issue with the swipe gesture recognizer in Xcode. What I want to let the code do is the following: When you swipe upwards a view with floating buttons disappears. When you swipe downwards, the floating buttons appear again. But of course, it doesn't work :D </p>
  
  <p>I can change the position of the view manually in StoryBoard without messing the constraints up.</p>
  
  <p>Everything is connected properly.</p>
  
  <p>It doesn't give an error message either, just doesn't work.</p>
  
  <p>What can I do?</p>
  
  <p>I use the following code:</p>
  
  <pre><code>import UIKit
  
  class HomeViewController: UIViewController {
  
  
      @IBOutlet weak var BottomFloatersBottomLayoutGuide: NSLayoutConstraint!
  
  
      @IBAction func UpSwipe(_ sender: UISwipeGestureRecognizer) {
          BottomFloatersBottomLayoutGuide.constant = -400
      }
  
      @IBAction func DownSwipe(_ sender: UISwipeGestureRecognizer) {
                 BottomFloatersBottomLayoutGuide.constant = 0
      }
  }
  </code></pre>