title: Swift: change speed of a moveTo SKAction
body: <p>I have a simple sprite movement that I am triggering with the following line: </p>
  
  <pre><code>   actionMove = SKAction.moveTo(CGPoint(x: size.width + CGFloat(KUGELWIDTH / 2), y: yPos), duration: NSTimeInterval(actualDuration))
  </code></pre>
  
  <p>And then i call <code>runAction</code> in the following manner: </p>
  
  <pre><code>  let actionMoveDone = SKAction.removeFromParent()
    kugel.runAction(SKAction.sequence([actionMove, actionMoveDone]))
  </code></pre>
  
  <p>What i am confused about, is changing the speed (duration) of the <code>SKAction</code> in the middle of while it is in the middle of running. This may be impossible, in which case, is there another method to invoke to move a sprite around my <code>Scene</code> with which I can change the Sprite's speed in the middle of its movement? </p>