//如何制作入场动画
let rect = CGRect(x: 0, y: 100, width: 320, height: 320)
let myView = UIView(frame: rect)
myView.backgroundColor = UIColor.red
self.view.addSubview(myView)
//初始化一个过度动画实例
let animation = CATransition()
//设置动画时常为两秒
animation.duration = 2
//设置动画速度为由慢到快
animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
//设置动画类型为入场动画
animation.type = CATransitionType.push
//将动画指定给图像视图的层
myView.layer.add(animation, forKey: "Push")