//需要设置转场动画的控制器titleViewVc.transitioningDelegate = aniamator//这里的animator是animator的实例

class animatorTool: NSObject {
 lazy var isPresent = false
 var callBack : ((isPresented:Bool)->())?//向外界传递动画是否正在显示

 init(callBack : ((isPresented:Bool)->())) {
  self.callBack = callBack
 }//自定义构造方法，便于给闭包赋值
}
extension animatorTool:UIViewControllerTransitioningDelegate{
 func presentationControllerForPresentedViewController(presented: UIViewController, presentingViewController presenting: UIViewController, sourceViewController source: UIViewController) -> UIPresentationController? {
  return AWYPresentationController(presentedViewController: presented, presentingViewController: presenting)//AWYPresentationController是自定义继承自UIPresentationController的类，是为了设置modal出来的vc的view的大小
 }
 func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
  isPresent = true
  self.callBack!(isPresented: isPresent)
  return self
 }

 func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
  isPresent = false
  self.callBack!(isPresented: isPresent)
  return self
 }
}

extension animatorTool:UIViewControllerAnimatedTransitioning{
 func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
  return 0.5//动画时长
 }
 func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
  isPresent ?animatetransitionForPresented(transitionContext) : animatetransitionForDismissed(transitionContext)
 }

 func animatetransitionForPresented(transitonContext:UIViewControllerContextTransitioning){
  let aimView = transitonContext.viewForKey(UITransitionContextToViewKey)!
  transitonContext.containerView()?.addSubview(aimView)

  aimView.transform = CGAffineTransformMakeScale(1.0, 0.0)
  UIView.animateWithDuration(transitionDuration(transitonContext), animations: {
   aimView.layer.anchorPoint = CGPointMake(0.5, 0.0)
   aimView.transform = CGAffineTransformIdentity
  }) { (_) in
   transitonContext.completeTransition(true)
  }
 }

 func animatetransitionForDismissed(transitonContext:UIViewControllerContextTransitioning){
  let aimView = transitonContext.viewForKey(UITransitionContextFromViewKey)!
  transitonContext.containerView()?.addSubview(aimView)


  UIView.animateWithDuration(transitionDuration(transitonContext), animations: {
   aimView.layer.anchorPoint = CGPointMake(0.5, 0.0)
   aimView.transform = CGAffineTransformMakeScale(1.0, 0.001)//留一点值，这样会有动画效果
  }) { (_) in
   transitonContext.completeTransition(true)
  }

 }


}