public func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval

    // This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.

    public func animateTransition(transitionContext: UIViewControllerContextTransitioning)

    // This is a convenience and if implemented will be invoked by the system when the transition context's completeTransition: method is invoked.

    optional public func animationEnded(transitionCompleted: Bool)

UIViewControllerInteractiveTransitioning {

    // This is the non-interactive duration that was returned when the

    // animators transitionDuration: method was called when the transition started.

    public var duration: CGFloat { get }

    // The last percentComplete value specified by updateInteractiveTransition:

    public var percentComplete: CGFloat { get }

    // completionSpeed defaults to 1.0 which corresponds to a completion duration of

    // (1 - percentComplete)*duration.  It must be greater than 0.0. The actual

    // completion is inversely proportional to the completionSpeed.  This can be set

    // before cancelInteractiveTransition or finishInteractiveTransition is called

    // in order to speed up or slow down the non interactive part of the

    // transition.

    public var completionSpeed: CGFloat

    // When the interactive part of the transition has completed, this property can

    // be set to indicate a different animation curve. It defaults to UIViewAnimationCurveEaseInOut.

    // Note that during the interactive portion of the animation the timing curve is linear.

    public var completionCurve: UIViewAnimationCurve

    // These methods should be called by the gesture recognizer or some other logic

    // to drive the interaction. This style of interaction controller should only be

    // used with an animator that implements a CA style transition in the animator's

    // animateTransition: method. If this type of interaction controller is

    // specified, the animateTransition: method must ensure to call the

    // UIViewControllerTransitionParameters completeTransition: method. The other

    // interactive methods on UIViewControllerContextTransitioning should NOT be

    // called.

    public func updateInteractiveTransition(percentComplete: CGFloat)

    public func cancelInteractiveTransition()

    public func finishInteractiveTransition()

@available(iOS 2.0, *)

    optional public func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning?

    @available(iOS 2.0, *)

    optional public func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning?

    optional public func interactionControllerForPresentation(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?

    optional public func interactionControllerForDismissal(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning?

    @available(iOS 8.0, *)

    optional public func presentationControllerForPresentedViewController(presented: UIViewController, presentingViewController presenting: UIViewController, sourceViewController source: UIViewController) -> UIPresentationController?

import UIKit

protocol SZAnimatorPresentDelegate: NSObjectProtocol {

    // 负责提供弹出动画的视图

    func presentView() -> UIView

    func presentFrameRect() -> CGRect

    func presentToRect() -> CGRect

}

protocol SZAnimatorDimissDelegate: NSObjectProtocol {

    // 负责提供dismiss动画的视图

    func dismissView() -> UIView

    func dismissFrameRect() -> CGRect

    func dismissToRect() -> CGRect

}

class SZAnimator: NSObject {

     var isPresent: Bool = true

    weak var presentDelegate: SZAnimatorPresentDelegate?

    weak var dismissDelegate: SZAnimatorDimissDelegate?

}

extension SZAnimator: UIViewControllerTransitioningDelegate {

    // 指定弹出时，处理动画的对象

    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {

        isPresent = true

        return self

    }

    // 指定弹下去时候, 处理动画的对象

    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {

        isPresent = false

        return self

    }

}

// 消失动画

// 弹出动画

extension SZAnimator: UIViewControllerAnimatedTransitioning {

    // 返回动画的时间

    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {

        return 2.0

    }

    // 在这里, 实现真正的弹出, 或者消失的动画

    // transitionContext

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {

        isPresent ? present(transitionContext) : dismiss(transitionContext)

    }

    func dismiss(transitionContext: UIViewControllerContextTransitioning) {

        // 自定义动画

        // 面向协议进行开发

        // 1. 拿什么界面做动画

        // 2. fromRect

        // 3. toRect

        let animationView = dismissDelegate!.dismissView()

        transitionContext.containerView()?.addSubview(animationView)

        // 初始的frame

        animationView.frame = dismissDelegate!.dismissFrameRect()

        // 最终需要展示的视图

        if #available(iOS 8.0, *) {

            let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey)

        // 动画

        UIView.animateWithDuration(transitionDuration(transitionContext), animations: {

//            toView?.alpha = 1

            animationView.frame = self.dismissDelegate!.dismissToRect()

            fromView?.alpha =

        }) { (flag: Bool) in

            animationView.removeFromSuperview()

            transitionContext.completeTransition(true)

        }

        }

    }

    func present(transitionContext: UIViewControllerContextTransitioning) {

        // 自定义动画

        // 面向协议进行开发

        // 1. 拿什么界面做动画

        // 2. fromRect

        // 3. toRect

        let animationView = presentDelegate!.presentView()

        transitionContext.containerView()?.addSubview(animationView)

        // 初始的frame

        animationView.frame = presentDelegate!.presentFrameRect()       

        // 最终需要展示的视图

        if #available(iOS 8.0, *) {

            let toView = transitionContext.viewForKey(UITransitionContextToViewKey)

        toView?.frame = UIScreen.mainScreen().bounds

        transitionContext.containerView()?.addSubview(toView!)

        toView?.alpha = 

        // 动画

        UIView.animateWithDuration(2.0, animations: {

            toView?.alpha =

            animationView.frame = self.presentDelegate!.presentToRect()

        }) { (flag: Bool) in

            animationView.removeFromSuperview()

            transitionContext.completeTransition(true)

        }

        }

    }

}