Swift 2.1 为 UIView 添加点击事件和点击效果

extension UIView {

  func addOnClickListener(target: AnyObject, action: Selector) {
    let gr = UITapGestureRecognizer(target: target, action: action)
    gr.numberOfTapsRequired = 1
    userInteractionEnabled = true
    addGestureRecognizer(gr)
  }

}

class UIViewEffect : UIView {

  override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    backgroundColor = UIColor.groupTableViewBackgroundColor()
  }

  override func touchesCancelled(touches: Set<UITouch>?, withEvent event: UIEvent?) {
    UIView.animateWithDuration(0.15, animations: { () -> Void in
      self.backgroundColor = UIColor.clearColor()
    })
  }

  override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
    UIView.animateWithDuration(0.15, animations: { () -> Void in
      self.backgroundColor = UIColor.clearColor()
    })
  }
}