自定义转场动画

public func presentViewController(viewControllerToPresent: UIViewController, animated flag: Bool, completion: (() -> Void)?)

public func dismissViewControllerAnimated(flag: Bool, completion: (() -> Void)?)

// return:Present时的动画管理器
    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        
        let animator = TransitionAnimator()
        // animator就是相对应的管理器，管理器的具体实现请往下看
        animator.transition = .Present
        
        return animator
        
    }
 // return:Dismiss时的动画管理器   
    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        
        let animator = TransitionAnimator()
        
        animator.transition = .Dismiss
        
        return animator
    }

// 转场动画持续的时间
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval{
        
        return 2.0
    }
    
//  转场动画具体的实现
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
    
        //                    present  dismiss
        // fromViewController    A        B
        // toViewController      B        A
        
        let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)
        toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
  // 转成动画中的容器View
        let containerView = transitionContext.containerView()
        
        let fromView = fromViewController?.view
        let toView = toViewController?.view
        
        //  transition 是自己写的属性，用来分别是present和Dismiss
        if self.transition == .Present{
   
            presentAnimation(transitionContext, fromView: fromView!, toView: toView!, containerView: containerView!,fromController: fromViewController!, toController: toViewController!)
            
        }else{
            
            dismissAnimation(transitionContext, fromView: fromView!, toView: toView!, containerView: containerView!, fromController: fromViewController!, toController: toViewController!)
        }
        

    }

        // present 动画的实现
    func presentAnimation(transitionContext:UIViewControllerContextTransitioning,fromView:UIView,toView:UIView,containerView:UIView,fromController:UIViewController,toController:UIViewController){
        
        // 设置B控制器的锚点为右上角
        toView.layer.anchorPoint = CGPoint(x: 1, y: 0)
        // 可以获得B控制器最终的frame
        toView.frame = transitionContext.finalFrameForViewController(toController)
  // 将B控制器的View 添加的containerView上
        containerView.addSubview(toView)
        
        // 使B控制器逆时针旋转90度
        toView.layer.transform = CATransform3DMakeRotation(-CGFloat(M_PI_2), 0, 0, 1)
        toView.alpha = 0
        
        let transitionDuration = self.transitionDuration(transitionContext)

// 弹性动画
        UIView.animateWithDuration(transitionDuration,  // 持续时间
        delay: 0,  // 延迟多久执行
        usingSpringWithDamping: 0.6, // 弹性强度
         initialSpringVelocity: 0,  // 初始速度
         options: .CurveLinear,  // 弹性方案
         animations: { () -> Void in
            
            toView.alpha = 1
            toView.layer.transform = CATransform3DIdentity

            }) { (finished: Bool) -> Void in
            //再完成之后，记得去实现转场动画结束的方法
                let wasCancelled = transitionContext.transitionWasCancelled()
                transitionContext.completeTransition(!wasCancelled)
        }
        
    }
    
    func dismissAnimation(transitionContext:UIViewControllerContextTransitioning,fromView:UIView,toView:UIView,containerView:UIView,fromController:UIViewController,toController:UIViewController){
        
        let transitionDuration = self.transitionDuration(transitionContext)
        
        // 将A控制器的View添加到B控制器之下
        containerView.insertSubview(toView, belowSubview: fromView)
        
        UIView.animateWithDuration(transitionDuration * 0.5, animations: { () -> Void in
            
            fromView.layer.transform = CATransform3DMakeRotation(-CGFloat(M_PI_2), 0, 0, 1)
            fromView.alpha = 0
            
            }) { (finished: Bool) -> Void in
                
                let wasCancelled = transitionContext.transitionWasCancelled()
                transitionContext.completeTransition(!wasCancelled)
        }
       
        
    }

func animationEnded(transitionCompleted: Bool) {
    toVC.endAppearanceTransition()
}

func interactionControllerForPresentation(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?{
    // isPanGestureRecognizer是用来判断我是用手势还是用的按钮执行的present的动画
    return self.isPanGestureRecognizer ? InteractionController.init(gesture: self.gesture) : nil
    
}

/// 当手势有滑动时触发这个函数
func gestureAction(gestureRecognizer: UIScreenEdgePanGestureRecognizer) {
    switch gestureRecognizer.state {
    case .Began: break
    // 在此更新转成动画的进度，percentForGesture方法是自己写的用来计算进度的值，可以自行设置，具体内容请看demo
    case .Changed: self.updateInteractiveTransition(self.percentForGesture(gesture))  //更新进度
    case .Ended:
        // 手势滑动超过5分之一的时候完成转场,否则取消转场动画
        if self.percentForGesture(gestureRecognizer) >= 0.2 {
            self.finishInteractiveTransition()
        }else {
            self.cancelInteractiveTransition()
        }
    default: self.cancelInteractiveTransition()
        
    }
}

func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning?{
     
     if operation == .Push{
         let animator = TransitionAnimator()
         
         animator.transition = .Present
         
         return animator
     }else{
         return nil
     }
     
 }