title: Animate UIView height when using auto layout with swift
body: <p>Before Auto-layout, I've been animating a background's height in a project by setting the frame over <code>animateWithDuration</code>.</p>
  
  <pre><code>func setUpBackground() {
      self.backgroundView.frame = CGRect(x: 0, y: 0, width: 320, height: 10)
      self.backgroundView.backgroundColor = UIColorFromRGB(0x2d2d2d).CGColor
  }
  
  func AnimateBackgroundHeight() {
      UIView.animateWithDuration(0.5, animations: {
          self.backgroundView.frame = CGRect(x: 0, y: 0, width: 320, height: 600)    
      })
  }
  </code></pre>
  
  <p>After I converted my project to auto layout, I noticed that the animation occurs but the background height snaps back to the original size/style (interface builder setting) after. I read that when Auto-layout is turned on, the constraints will overwrite setting the <code>UIView</code> dimensions with <code>CGRect</code>.</p>
  
  <p>Therefore I'm wondering how to go about achieving the same height change animation effect with Auto-layout ON.</p>