// Any animations specified will be run in the same animation context as the

// transition. If the animations are occurring in a view that is a not

// descendent of the containerView, then an ancestor view in which all of the

// animations are occuring should be specified.  The completionBlock is invoked

// after the transition completes. (Note that this may not be after all the

// animations specified by to call complete if the duration is not inherited.)

// It is perfectly legitimate to only specify a completion block. This method

// returns YES if the animations are successfully queued to run. The completions

// may be run even if the animations are not. Note that for transitioning

// animators that are not implemented with UIView animations, the alongside

// animations will be run just after their animateTransition: method returns.

//

- (BOOL)animateAlongsideTransition:(void (^ __nullable)(id <UIViewControllerTransitionCoordinatorContext>context))animation

                        completion:(void (^ __nullable)(id <UIViewControllerTransitionCoordinatorContext>context))completion;

// This alternative API is needed if the view is not a descendent of the container view AND you require this animation

// to be driven by a UIPercentDrivenInteractiveTransition interaction controller.

- (BOOL)animateAlongsideTransitionInView:(nullable UIView *)view

                               animation:(void (^ __nullable)(id <UIViewControllerTransitionCoordinatorContext>context))animation

                              completion:(void (^ __nullable)(id <UIViewControllerTransitionCoordinatorContext>context))completion;

// When a transition changes from interactive to non-interactive then handler is

// invoked. The handler will typically then do something depending on whether or

// not the transition isCancelled. Note that only interactive transitions can

// be cancelled and all interactive transitions complete as non-interactive

// ones. In general, when a transition is cancelled the view controller that was

// appearing will receive a viewWillDisappear: call, and the view controller

// that was disappearing will receive a viewWillAppear: call.  This handler is

// invoked BEFORE the "will" method calls are made.

- (void)notifyWhenInteractionEndsUsingBlock: (void (^)(id <UIViewControllerTransitionCoordinatorContext>context))handler NS_DEPRECATED_IOS(7_0, 10_0,"Use notifyWhenInteractionChangesUsingBlock");

// This method behavior is identical to the method above. On 10.0, however, the behavior has

// changed slightly to account for the fact that transitions can be interruptible. For interruptible transitions

// The block may be called multiple times. It is called each time the transition moves from an interactive to a

// non-interactive state and vice-versa. The block is now also retained until the transition has completed.

- (void)notifyWhenInteractionChangesUsingBlock: (void (^)(id <UIViewControllerTransitionCoordinatorContext>context))handler NS_AVAILABLE_IOS(10_0);

/**

 初始化

 @param  presentedViewController  presentedViewController  跳转到这个控制器

 @param  presentingViewController presentingViewController 由这个控制器开始跳转

 @return return value description

 */

- (instancetype)initWithPresentedViewController:(UIViewController *)presentedViewController presentingViewController:(nullable UIViewController *)presentingViewController{

        self =[super initWithPresentedViewController:presentedViewController presentingViewController:presentingViewController];

        if (self) {

                // 自定义modalPresentationStyle

                presentedViewController.modalPresentationStyle= UIModalPresentationCustom;

        }

        return self;

}

/* present将要执行时 */

- (void)presentationTransitionWillBegin

{

        // 设置presentationWrappingView和dimmingView的UI效果

        UIView * presentedViewControllerView = [super presentedView];

        presentedViewControllerView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

        {

                //

                UIView *presentationWrapperView = [[UIView alloc] initWithFrame:self.frameOfPresentedViewInContainerView];

                presentationWrapperView.layer.shadowOpacity = 0.44f;  //设置阴影的透明度(0~1之间，0表示完全透明)

                presentationWrapperView.layer.shadowRadius  = 13.f;   //设置阴影的圆角

                //设置阴影的偏移量，如果为正数，则代表为往右边偏移

                presentationWrapperView.layer.shadowOffset  = CGSizeMake(0, -6.f);

                self.presentationWrappingView = presentationWrapperView;

                // 圆角View

                UIView *presentationRoundedCornerView = [[UIView alloc] initWithFrame:UIEdgeInsetsInsetRect(presentationWrapperView.bounds, UIEdgeInsetsMake(0, 0, -CORNER_RADIUS, 0))];

                // autoresizingMask 这个属性 自动调整与父视图之间的边界距离

                presentationRoundedCornerView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

                presentationRoundedCornerView.layer.cornerRadius = CORNER_RADIUS;

                presentationRoundedCornerView.layer.masksToBounds = YES;

                [presentationRoundedCornerView addSubview:presentedViewControllerView];

                //*** presentedViewControllerView

                presentedViewControllerView.frame = UIEdgeInsetsInsetRect(presentationRoundedCornerView.bounds, UIEdgeInsetsMake(0, 0, CORNER_RADIUS, 0));

                // ******************

                [presentationWrapperView addSubview:presentationRoundedCornerView];

        }

        {

                // 背景图

                UIView *dimmingView = [[UIView alloc] initWithFrame:self.containerView.bounds];

                dimmingView.backgroundColor = [UIColor blackColor];

                dimmingView.opaque = NO;

                dimmingView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;

                [dimmingView addGestureRecognizer:[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(dimmingViewTapped:)]];

                self.dimmingView = dimmingView;

                [self.containerView addSubview:dimmingView];

                id<UIViewControllerTransitionCoordinator> transitionCoordinator = self.presentingViewController.transitionCoordinator;

                self.dimmingView.alpha = 0.f;

                [transitionCoordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext> context) {

                        self.dimmingView.alpha = 0.5f;

                } completion:NULL];

        }

}

 BOOL isPresent   = (toViewController.presentingViewController == fromViewController);

        UIView *tempView = nil;

        if (isPresent) {

           tempView = [fromViewController.view snapshotViewAfterScreenUpdates:NO];

           tempView.frame = fromViewController.view.frame;

           fromViewController.view.hidden = YES;

           [contextView addSubview:tempView];

           [contextView addSubview:toViewController.view];

           toViewController.view.frame = CGRectMake(0, contextView.frame.size.height, contextView.frame.size.width, 400);

        }else{

                //参照present动画的逻辑，present成功后，containerView的最后一个子视图就是截图视图，我们将其取出准备动画

                NSArray *subviewsArray = contextView.subviews;

                tempView = subviewsArray[MIN(subviewsArray.count, MAX(0, subviewsArray.count - 2))];

        }

-(void)presentNextControllerClicked{

    // 既然这里是导航控制器的转场，就要给导航设置代理。然后在第二个控制器遵守相应的协议之后，判断

    // 是Push还是Pop,执行相应的动画

    PageToViewController * pushVC = [PageToViewController new];

    self.navigationController.delegate = pushVC;

    [self.navigationController pushViewController:pushVC animated:YES];

}

#pragma mark - UINavigationControllerDelegate

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC{

    //分pop和push两种情况分别返回动画过渡代理相应不同的动画操作

    return [[PageAnimation alloc]initWith:operation == UINavigationControllerOperationPush ? Push_type : Pop_type];

}