title: Rotating a UIButton by 90 degrees every time the button is clicked
body: <p>How do you rotate a UIButton by 90 degrees each time the button is clicked and also keep track of each rotated position/angle?</p>
  
  <p>Here is the code I have so far but it only rotates once:</p>
  
  <pre><code>@IBAction func gameButton(sender: AnyObject) {
      UIView.animateWithDuration(0.05, animations: ({
          self.gameButtonLabel.transform = CGAffineTransformMakeRotation(CGFloat(M_PI_2))
      }))
  }
  </code></pre>