title: CABasicAnimation autoreverse twice as fast
body: <p>I'm using this code to add pulsing circle with autoreverse:</p>
  
  <pre><code>let scaleAnimation = CABasicAnimation(keyPath: "transform.scale")        
  scaleAnimation.duration = 6
  scaleAnimation.repeatCount = 200
  scaleAnimation.autoreverses = true
  scaleAnimation.fromValue = 0.1
  scaleAnimation.toValue = 0.8
  scaleAnimation.timingFunction = CAMediaTimingFunction(controlPoints: 0.42, 0.0, 0.58, 1.0)
  animationView.layer.add(scaleAnimation, forKey: "scale")
  </code></pre>
  
  <p>What I would like to do here is to:</p>
  
  <p>Run animation <code>fromValue = 0.1</code> <code>toValue = 0.8</code> at <code>2x speed</code>, 
  and go backwards animating it <code>fromValue = 0.8</code> <code>toValue = 0.1</code> at <code>1x speed</code>.</p>
  
  <p>Is there an easy way to achieve this? </p>