extension UIViewController { public var yy_routerAnimation : YYTransition {  set {   objc_setAssociatedObject(self, &YYTransitionKey.kRouterAnimationKey, newValue, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)  }  get {   guard let r = objc_getAssociatedObject(self, &YYTransitionKey.kRouterAnimationKey) as? YYTransition else {    return YYTransition()   }   return r  } }}

public class YYTransition: NSObject

extension YYTransition: UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate, UINavigationControllerDelegate

  return self }  public func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {  return 轉場動畫所需時間 }

 public func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {  switch self.yy_ransitionAnimationType {  case .circle:   break  case .move:   break  case .middle:   break  case .tier:   break  } }

extension YYTransition { // 是push還是pop public var yy_isBack: Bool {} // 動畫類型 var yy_ransitionAnimationType: YYTransitionAnimationType {} // 源view名字  var yy_fromViewPath: String? { } // 目標view名字  var yy_toViewPath: String? { } // 句柄 var yy_transitionContext: UIViewControllerContextTransitioning {}}

extension YYTransition: CAAnimationDelegate { public func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {  yy_transitionContext.completeTransition(!yy_transitionContext.transitionWasCancelled)  yy_transitionContext.viewController(forKey: .from)?.view.layer.mask = nil  yy_transitionContext.viewController(forKey: .to)?.view.layer.mask = nil }}

extension YYTransition { func maskAnimation(targetVC: UIViewController, startPath: UIBezierPath, endPath: UIBezierPath, context: UIViewControllerContextTransitioning) {}

YYTransition+CircleYYTransition+MoveYYTransition+TierYYTransition+Middle

UIViewControllerContextTransitioning 調用public func viewController(forKey key: UITransitionContextViewControllerKey) -> UIViewController?UIViewController調用open func value(forKeyPath keyPath: String) -> Any?* When requesting a snapshot, 'afterUpdates' defines whether the snapshot is representative of what's currently on screen or if you wish to include any recent changes before taking the snapshot. open func snapshotView(afterScreenUpdates afterUpdates: Bool) -> UIView?open func convert(_ rect: CGRect, from view: UIView?) -> CGRectopen func insertSubview(_ view: UIView, belowSubview siblingSubview: UIView)// This must be called whenever a transition completes (or is cancelled.) // Typically this is called by the object conforming to the // UIViewControllerAnimatedTransitioning protocol that was vended by the transitioning // delegate. For purely interactive transitions it should be called by the // interaction controller. This method effectively updates internal view // controller state at the end of the transition.public func completeTransition(_ didComplete: Bool)