title: Moving a UIImageView along UIBezierPath with CAKeyframeAnimation does nothing
body: <p>I'm trying to move a <code>UIImageView</code> along a <code>UIBezierPath</code> by using <code>CAKeyframeAnimation</code> in this function. Currently it doesn't move at all. I know the path creation is right because I'm drawing it to check and it's a nice arc in the shape I want.</p>
  
  <p>Code:</p>
  
  <pre><code>func animateSun() {
      let sunImageView = UIImageView(image: UIImage(named: "Sun"))
      sunImageView.sizeToFit()
  
      let sunAnimationPath = UIBezierPath()
      let pathStart = CGPoint(x: (sunImageView.frame.width / 2), y: self.view.frame.height - (self.rearMountainView.frame.height / 2) + sunImageView.frame.height)
      let pathEnd = CGPoint(x: self.view.frame.width - (sunImageView.frame.width / 2), y: self.view.frame.height - (self.rearMountainView.frame.height / 2) + (sunImageView.frame.height))
  
      sunAnimationPath.moveToPoint(pathStart)
  
      let controlOne = CGPoint(x: pathStart.x, y: pathStart.y - 500)
      let controlTwo = CGPoint(x: pathEnd.x, y: pathEnd.y - 500)
  
      sunAnimationPath.addCurveToPoint(pathEnd, controlPoint1: controlOne, controlPoint2: controlTwo)
  
      sunImageView.frame = CGRectMake(pathStart.x - (sunImageView.frame.width / 2), pathStart.y - (sunImageView.frame.height / 2), sunImageView.frame.width, sunImageView.frame.height)
  
      let animation = CAKeyframeAnimation(keyPath: "day")
      animation.duration = 15
      animation.repeatCount = 0
      animation.path = sunAnimationPath.CGPath
      animation.calculationMode = kCAAnimationPaced
      animation.fillMode = kCAFillModeForwards
      animation.removedOnCompletion = false
  
      sunImageView.layer.addAnimation(animation, forKey: "day")
      self.view.addSubview(sunImageView)
      //self.view.sendSubviewToBack(sunImageView)
  
      let layer          = CAShapeLayer()
      layer.path          = sunAnimationPath.CGPath
      layer.strokeColor   = UIColor.blackColor().CGColor
      layer.lineWidth     = 1.0
      layer.fillColor     = nil
  
      self.view.layer.addSublayer(layer)
  }
  </code></pre>