用UIImageView实现几张图片轮转已达到动画效果

let imageView = UIImageView(frame: CGRect(x:0 , y: 5, width: 100, height: 100))
self.view.addSubview(imageView)
let imageArray = NSArray(objects: UIImage(named: "codeing1.png")!,UIImage(named: "codeing2.png")!,UIImage(named: "codeing3.png")!,UIImage(named: "codeing4.png")!)
imageView.animationImages = imageArray as? [UIImage]
imageView.animationDuration = 1.0
imageView.animationRepeatCount = 0
imageView.startAnimating()