class AnimatedTransitioning: NSObject {
 var isPresenting: Bool = false
}
extension AnimatedTransitioning: UIViewControllerAnimatedTransitioning {
 func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
 return 0.5
 }
 func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
 let fromView = transitionContext.view(forKey: .from)!
 let toView = transitionContext.view(forKey: .to)!
 let containerView = transitionContext.containerView
 if isPresenting {
  toView.transform = CGAffineTransform(scaleX: 0, y: 0)
  containerView.addSubview(toView)
 } else {
  containerView.insertSubview(toView, belowSubview: fromView)
 }
 UIView.animate(withDuration: 0.5, animations: {
  if self.isPresenting {
  toView.transform = CGAffineTransform.identity
  } else {
  fromView.transform = CGAffineTransform(scaleX: 0.001, y: 0.001)
  }
 }) { (finished) in
  transitionContext.completeTransition(finished)
 }
 }
}

class CustomTransitioningDelegate: NSObject, UIViewControllerTransitioningDelegate {
 func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
 let at = AnimatedTransitioning()
 at.isPresenting = true
 return at
 }
 func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
 let at = AnimatedTransitioning()
 at.isPresenting = false
 return at
 }
}

class ViewController: UIViewController {
 // 必须保存为实例变量
 var ctDelegate = CustomTransitioningDelegate()
 override func touchesBegan(_ touches: Set, with event: UIEvent?) {
 let vc = TempViewController()
 vc.transitioningDelegate = ctDelegate
 self.present(vc, animated: true, completion: nil)
 }
}