title: Animate view height with Swift
body: <p>I have view <strong>sView</strong> inside my ViewController. It height has constraint - I created IBOutlet for this constraint - <strong>sViewHeightConstraint</strong>. I want to decrease height of sView with animation.</p>
  
  <p>I created function</p>
  
  <pre><code>UIView.animateWithDuration(5.5, animations: {
                  self.sViewHeightConstraint.constant = 50
              })
  </code></pre>
  
  <p>Height of view is changing but i don't see any animation. What I am doing wrong?</p>