iOS自定义转场动画

通过这几天的学习，我尝试实现了四个效果，废话不多说，先上效果图：

DEMO ONE：一个神奇移动效果push动画，支持手势pop

神奇效果.gif

DEMO TWO：一个弹性的present动画，支持手势present和dismiss

弹性present.gif

DEMO THREE：一个翻页push效果，支持手势PUSH和POP

翻页效果.gif

DEMO FOUR：一个小圆点扩散present效果，支持手势dimiss

小圆点扩散.gif

准备

从iOS7开始,苹果提供了自定义转场的API,模态推送present和dismiss,导航控制器的push和pop,标签控制器的控制器切换都可以自定义转场了.
1.我们需要自定义一个遵循的<UIViewControllerAnimatedTransitioning>协议的动画过渡管理对象，并实现两个必须实现的方法：

 // 返回动画事件
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext; 
// 所有的过渡动画事务都在这个方法里面完成 
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

2.我们还需要自定义一个继承于UIPercentDrivenInteractiveTransition的手势过渡管理对象，我把它成为百分比手势过渡管理对象，因为动画的过程是通过百分比控制的
3.成为相应的代理，实现相应的代理方法，返回我们前两步自定义的对象就OK了 ！
模态推送需要实现如下4个代理方法，iOS8新的那个方法我暂时还没有发现它的用处，所以暂不讨论.

//返回一个管理present动画过渡的对象
- (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source;
//返回一个管理dismiss动画过渡的对象
- (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed;
//返回一个管理present手势过渡的对象
- (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id <UIViewControllerAnimatedTransitioning>)animator;
//返回一个管理dismiss动画过渡的对象
- (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id <UIViewControllerAnimatedTransitioning>)animator;

导航控制器实现如下2个代理方法

//返回转场动画过渡管理对象
- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
                          interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);
//返回手势过渡管理对象
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
                                   animationControllerForOperation:(UINavigationControllerOperation)operation
                                                fromViewController:(UIViewController *)fromVC
                                                  toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

标签控制器也有相应的两个方法

//返回转场动画过渡管理对象
 - (nullable id <UIViewControllerInteractiveTransitioning>)tabBarController:(UITabBarController *)tabBarController
               interactionControllerForAnimationController: (id <UIViewControllerAnimatedTransitioning>)animationController NS_AVAILABLE_IOS(7_0);
 //返回手势过渡管理对象
 - (nullable id <UIViewControllerAnimatedTransitioning>)tabBarController:(UITabBarController *)tabBarController
     animationControllerForTransitionFromViewController:(UIViewController *)fromVC
                                       toViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

4.如果看着这些常常的代理方法名头疼的话，没关系，先在demo中用起来吧，慢慢就习惯了，其实哪种自定义转场都只需要这3个步骤，如果不需要手势控制，步骤2还可以取消，现在就让我们动手来实现效果吧

Let's go!

DEMO ONE：神奇移动效果

1.我们首先创建2个控制器，为了方便我称做present操作的为vc1、被present的为vc2，点击一个控制器上的按钮可以push出另一个控制器.
2.创建一个手势过渡管理的类，我这里是PEInteractiveTransition,因为无论哪一种转场，手势控制的实质都是一样的，我干脆就把这个手势过渡管理的类封装了一下，具体可以在.h文件里面查看，在接下来的三个转场效果中我们都可以便捷的是使用它：
PEInteractiveTransition.h

typedef void(^GestureConfig)();

//手势转场类型
typedef NS_ENUM(NSUInteger,PEInteractiveTransitionType){
    PEInteractiveTransitionTypePresent = 0,
    PEInteractiveTransitionTypeDismiss,
    PEInteractiveTransitionTypePush,
    PEInteractiveTransitionTypePop
};

//手势方向
typedef NS_ENUM(NSUInteger,PEInteractiveTransitionGestureDirection){
    PEInteractiveTransitionGestureDirectionLeft = 0,
    PEInteractiveTransitionGestureDirectionRight,
    PEInteractiveTransitionGestureDirectionUp,
    PEInteractiveTransitionGestureDirectionDown
};

@interface PEInteractiveTransition : UIPercentDrivenInteractiveTransition
/** 记录是否开始手势,判断pop操作是手势出发还是返回键出发 */
@property (nonatomic, assign)BOOL interation;
/** 触发手势present的时候config,在config中初始化并present需要弹出的控制器 */
@property (nonatomic, copy)GestureConfig presentConfig;
/** 触发手势push的时候config,在config中初始化并push需要弹出的控制器 */
@property (nonatomic, copy)GestureConfig pushConfig;

#pragma mark - ---初始化方法---
+ (instancetype)interactiveTransitionWithTransitionType:(PEInteractiveTransitionType)type GestureDirection:(PEInteractiveTransitionGestureDirection)direction;
- (instancetype)initWithTransitionType:(PEInteractiveTransitionType)type GestureDirection:(PEInteractiveTransitionGestureDirection)direction;

/** 给传入控制器添加手势*/
- (void)addPanGestureForViewController:(UIViewController *)viewController; 
@end

PEInteractiveTransition.m

#import "PEInteractiveTransition.h"

@interface PEInteractiveTransition()

/** 传入的ViewController */
@property (nonatomic, weak)UIViewController *vc;
/** 手势方向 */
@property (nonatomic, assign)PEInteractiveTransitionGestureDirection direction;
/** 手势类型 */
@property (nonatomic, assign)PEInteractiveTransitionType type;

@end
@implementation PEInteractiveTransition

+ (instancetype)interactiveTransitionWithTransitionType:(PEInteractiveTransitionType)type GestureDirection:(PEInteractiveTransitionGestureDirection)direction
{
    return [[self alloc] initWithTransitionType:type GestureDirection:direction];
}

- (instancetype)initWithTransitionType:(PEInteractiveTransitionType)type GestureDirection:(PEInteractiveTransitionGestureDirection)direction{
    self = [super init];
    if (self) {
        _direction = direction;
        _type = type;
    }
    return self;
}

- (void)addPanGestureForViewController:(UIViewController *)viewController
{
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleGesture:)];
    self.vc = viewController;
    [viewController.view addGestureRecognizer:pan];
}
/**
 *  手势过渡过程
 *
 *  @param pan 添加的手势
 */
- (void)handleGesture:(UIPanGestureRecognizer *)pan
{
    //手势百分比 初始化为0  向上和向右滑动 距离是负的 所以前面加负号 这样负负得正
    CGFloat persent = 0;
    switch (_direction) {
        case PEInteractiveTransitionGestureDirectionUp:{
            CGFloat transitionY = -[pan translationInView:pan.view].y;
            persent = transitionY / pan.view.frame.size.width;
        }
            break;
        case PEInteractiveTransitionGestureDirectionRight:{
            CGFloat transitionR = [pan translationInView:pan.view].x;
            persent = transitionR / pan.view.frame.size.width;
        }
            break;
        case PEInteractiveTransitionGestureDirectionDown:{
            CGFloat transitionD = [pan translationInView:pan.view].y;
            persent = transitionD / pan.view.frame.size.width;
        }
            break;
        case PEInteractiveTransitionGestureDirectionLeft:{
            CGFloat transitionL = -[pan translationInView:pan.view].x;
            persent = transitionL / pan.view.frame.size.width;
        }
            break;
            
        default:
            break;
    }
    switch (pan.state) {
        case UIGestureRecognizerStateBegan:{
            //手势开始的时候标记手势状态,并开始相应的事件
            self.interation = YES;
            [self startGesture];
        }
            break;
        case UIGestureRecognizerStateChanged:{
            //手势过程中,通过updateInteractiveTransition设置pop过程进行的百分比
            [self updateInteractiveTransition:persent];
        }
            break;
        case UIGestureRecognizerStateEnded:{
            //手势完成后结束标记并且判断移动的距离是否过半,过则finishInteractiveTransition完成转场操作,否则取消转场操作
            self.interation = NO;
            if (persent > 0.5) {
                [self finishInteractiveTransition];
            }else {
                [self cancelInteractiveTransition];
            }
        }
            break;
            
        default:
            break;
    }
}

- (void)startGesture
{
    switch (_type) {
        case PEInteractiveTransitionTypePresent:{
            if (_presentConfig) {
                _presentConfig();
            }
        }
            break;
        case PEInteractiveTransitionTypeDismiss:{
            [_vc dismissViewControllerAnimated:YES completion:nil];
        }
            break;
        case PEInteractiveTransitionTypePush:{
            if (_pushConfig) {
                _pushConfig();
            }
        }
            break;
        case PEInteractiveTransitionTypePop:{
            [_vc.navigationController popViewControllerAnimated:YES];
        }
            break;
            
        default:
            break;
    }
}

@end

3.创建神奇效果的具体动画代理
PENaviTransition.h

typedef NS_ENUM(NSUInteger, PENaviTransitionType){
    PENaviTransitionTypePush = 0,
    PENaviTransitionTypePop
};

@interface PENaviTransition : NSObject<UIViewControllerAnimatedTransitioning>


+ (instancetype)transitionWithType:(PENaviTransitionType)type;
- (instancetype)initWithTransitionType:(PENaviTransitionType)type;

@end

PENaviTransition.m主要实现一个动画时长方法和一个push动画和一个pop动画

/**
 *  动画时长
 */
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.75;
}
/**
 *  如何执行过渡动画
 */
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    switch (_type) {
        case PENaviTransitionTypePush:
            [self doPushAnimation:transitionContext];
            break;
        case PENaviTransitionTypePop:
            [self doPopAnimation:transitionContext];
            break;
            
        default:
            break;
    }
}

/**
 *  执行push过渡动画
 */
- (void)doPushAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    PEMagicMoveController *fromVC = (PEMagicMoveController *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    PEMagicMovePushController *toVC = (PEMagicMovePushController *)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    //拿到当前点击的cell的imageView
    PEMagicMoveCell *cell = (PEMagicMoveCell *)[fromVC.collectionView cellForItemAtIndexPath:fromVC.clickIndex];
    UIView *containerView = [transitionContext containerView];
    UIView *tempView = [cell.imageV snapshotViewAfterScreenUpdates:NO];
    //将点击的cell截图作为临时View的内容 并将坐标系转化成push控制器种的坐标
    tempView.frame = [cell.imageV convertRect:cell.imageV.bounds toView:containerView];
    //设置动画前的各个控件的状态
    cell.imageV.hidden = YES;
    toVC.view.alpha = 0;
    toVC.imageView.hidden = YES;
    //tempView添加到containerView中保证在最前方,所以后添加
    [containerView addSubview:toVC.view];
    [containerView addSubview:tempView];
    //开始push动画
    [UIView animateWithDuration:[self transitionDuration:transitionContext] delay:0.0 usingSpringWithDamping:0.55 initialSpringVelocity:1/0.55 options:0 animations:^{
        //临时View(也就是截取cell大小)的frame变成和push出来view种的imageView大小一样
        tempView.frame = [toVC.imageView convertRect:toVC.imageView.bounds toView:containerView];
        //push控制器由透明为0变为1
        toVC.view.alpha = 1;
    } completion:^(BOOL finished) {
        tempView.hidden = YES;
        toVC.imageView.hidden = NO;
        //如果动画过渡取消了就标记不完成,否则标记完成,这里可以直接写YES,如果有手势过渡才需要判断,必须标记,否则系统不会完成动画,会出现无法交互等bug
        [transitionContext completeTransition:YES];
    }];
}
/**
 *  执行pop过渡动画
 */
- (void)doPopAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    PEMagicMovePushController *fromVC = (PEMagicMovePushController *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    PEMagicMoveController *toVC = (PEMagicMoveController *)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    PEMagicMoveCell *cell = (PEMagicMoveCell *)[toVC.collectionView cellForItemAtIndexPath:toVC.clickIndex];
    UIView *containerView = [transitionContext containerView];
    //这里的lastObject就是push适合初始化的那个tempView
    UIView *tempView = containerView.subviews.lastObject;
    //设置动画前状态
    cell.imageV.hidden = YES;       //列表页面的cell先隐藏
    fromVC.imageView.hidden = YES;  //当前页面的imageView也进行隐藏
    tempView.hidden = NO;           //最上面的临时View显示
    [containerView insertSubview:toVC.view atIndex:0];
    //开始pop动画
    [UIView animateWithDuration:[self transitionDuration:transitionContext] delay:0.0 usingSpringWithDamping:.55 initialSpringVelocity:1/0.55 options:0 animations:^{
        //将临时View的坐标和大小变成新坐标系中列表cell的坐标和大小
        tempView.frame = [cell.imageV convertRect:cell.imageV.bounds toView:containerView];
        //同时详情页面隐藏
        fromVC.view.alpha = 0;
    } completion:^(BOOL finished) {
        //加入了手势判断
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
        if ([transitionContext transitionWasCancelled]) {
            //手势取消了,原来隐藏的imageView要显示出来
            tempView.hidden = YES;
            fromVC.imageView.hidden = NO;
        }else{
            //手势成功
            cell.imageV.hidden = NO;        //列表点击的cell要显示
            [tempView removeFromSuperview]; //临时的要去除 因为下一次会重新生成 不会产生冗余
        }
    }];
}

4.现在可以在具体进行跳转的页面vc1进行使用

#pragma mark <UICollectionViewDelegate>
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    //记录点击的是列表的第几个 这样在返回动画的时候能用上
    _clickIndex = indexPath;
    PEMagicMovePushController *vc = [[PEMagicMovePushController alloc] init];
    //设置导航控制器的代理为推出的控制器,可以达到自定义不同控制器推出效果的目的
    self.navigationController.delegate = vc;
    [self.navigationController pushViewController:vc animated:YES];
}

5.在push出的页面vc2进行过渡动画的监听和实现

//返回手势过渡管理对象
- (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 [PENaviTransition transitionWithType:operation == UINavigationControllerOperationPush ? PENaviTransitionTypePush : PENaviTransitionTypePop];
}

//返回转场动画过渡管理对象
- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController
{
    //如果是手动出发则返回我们的UIPercentDrivenInteractiveTransition对象
    return _interactiveTransition.interation ? _interactiveTransition : nil;
}

6.完成,就是下面的效果

神奇效果.gif

DEMO TWO： 弹性present动画

1.创建两个控制器,手势管理类和DEMO ONE是同一个
2.自己具体的动画过渡实现presentAnimation和dismissAnimation两个方法

/**
 *  presentAnimation
 */
- (void)presentAnimation:(id<UIViewControllerContextTransitioning>)transitionContent
{
    UIViewController *toVC = [transitionContent viewControllerForKey:UITransitionContextToViewControllerKey];
    UIViewController *fromVC = [transitionContent viewControllerForKey:UITransitionContextFromViewControllerKey];
    //snapshotViewAfterScreenUpdates:可以对某个试图截图,我们采用对这个截图做动画代替直接对toVC做动画,因为在手势过渡中直接使用toVC动画会和手势有冲突,如果不需要实现手势的话,就可以不是用截图了
    UIView *tempView = [fromVC.view snapshotViewAfterScreenUpdates:NO];
    tempView.frame = fromVC.view.frame;
    //因为对截图做动画,fromVC开始是隐藏的
    fromVC.view.hidden = YES;
    //containerView:如果要对视图做转场动画,视图就必须加入containerView中才能进行,可以理解为containerView管理所有做转场动画的视图
    UIView *containerView = [transitionContent containerView];
    //将截图视图和toVC的view都加入containerView中 截图视图是fromVC所以先放 先放的在下面
    [containerView addSubview:tempView];
    [containerView addSubview:toVC.view];
    //设置toVC的frame,因为是present出来不是全屏,而且在底部,如果不设置默认是整个屏幕,这里的containerView的frame就是整个屏幕
    toVC.view.frame = CGRectMake(0, containerView.height, containerView.width, 500);
    //开始动画,使用产生弹簧效果的方法
    [UIView animateWithDuration:[self transitionDuration:transitionContent] delay:0.0 usingSpringWithDamping:0.55 initialSpringVelocity:1.0 / 0.55 options:0 animations:^{
        //1.让toVC向上移动 向上是负的
        toVC.view.transform = CGAffineTransformMakeTranslation(0, -500);
        //2.让截图视图缩小即可
        tempView.transform = CGAffineTransformMakeScale(0.85, 0.85);
        
    } completion:^(BOOL finished) {
        //使用如下代码标记整个转场过程是否正常完成[transitionContext transitionWasCancelled]代表手势是否取消了，如果取消了就传NO表示转场失败，反之亦然，如果不是用手势的话直接传YES也是可以的，我们必须标记转场的状态，系统才知道处理转场后的操作，否者认为你一直还在，会出现无法交互的情况
        [transitionContent completeTransition:![transitionContent transitionWasCancelled]];
        //转场失败后的处理
        if ([transitionContent transitionWasCancelled])
        {
            //失败后复原动画开始是的样子
            //1.把fromVC显示出来
            fromVC.view.hidden = NO;
            //2.移除截图视图,下次会重新生成
            [tempView removeFromSuperview];
        }
    }];
}

/**
 *  dismissAnimation
 */
- (void)dismissAnimation:(id<UIViewControllerContextTransitioning>)transitionContent
{
    UIViewController *fromVC = [transitionContent viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContent viewControllerForKey:UITransitionContextToViewControllerKey];
    
    //参照present动画的逻辑,present成功后,containerView的第一个子视图就是截图视图,我们将其取出做动画
    UIView *containerView = [transitionContent containerView];
    UIView *tempView = containerView.subviews[0];
    //开始动画
    [UIView animateWithDuration:[self transitionDuration:transitionContent] delay:0.0 usingSpringWithDamping:0.55 initialSpringVelocity:1 / 0.55 options:0 animations:^{
        //present使用的是transform,只需要恢复就可以了
        fromVC.view.transform = CGAffineTransformIdentity;
        tempView.transform = CGAffineTransformIdentity;
    } completion:^(BOOL finished) {
        if ([transitionContent transitionWasCancelled]) {
            //标记失败
            [transitionContent completeTransition:NO];
        }else{
            //成功后,标记成功,让toVC显示出来,并移除截图视图
            [transitionContent completeTransition:YES];
            toVC.view.hidden = NO;
            [tempView removeFromSuperview];
        }
    }];
}

3.vc1中进行调用

    PEElasticOneController *elasticVC = [PEElasticOneController new];
    elasticVC.delegate = self;
    [self presentViewController:elasticVC animated:YES completion:nil];

4.vc2中监听

#pragma mark - ---UIViewControllerTransitioningDelegate---
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
    return [PEElasticTransition transitionWithTransitionType:PEElasticTransitionTypePresent];
}
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
    return [PEElasticTransition transitionWithTransitionType:PEElasticTransitionTypeDismiss];
}
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)animator
{
    PEInteractiveTransition *interactivePresent = [self.delegate interactiveTransitionForPresent];
    return interactivePresent.interation ? interactivePresent : nil;
}
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator
{
    return self.interactiveTransition.interation ? self.interactiveTransition : nil;
}

这样就基本完成了

弹性present.gif

DEMO THREE:翻页push效果

1.其它和上面的相似,直接来看核心的过渡动画实现:

/**
 *  自定义push动画
 */
- (void)doPushAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    //对当前view截图 然后作为动画对象
    UIView *tempV = [fromVC.view snapshotViewAfterScreenUpdates:NO];
    tempV.frame = fromVC.view.frame;
    UIView *containerV = [transitionContext containerView];
    //临时的放最上面 做过渡
    [containerV addSubview:toVC.view];
    [containerV addSubview:tempV];
    fromVC.view.hidden = YES;
    //设置anchorPoint 选择的支点
    [tempV setAnchorPoint:CGPointMake(0, 0.5)];
    CATransform3D transform3d = CATransform3DIdentity;
    //m34（透视效果，要操作的这个对象要有旋转的角度，否则没有效果。正直/负值都有意义）;
    transform3d.m34 = -0.002;
    containerV.layer.sublayerTransform = transform3d;
    //增加阴影
    CAGradientLayer *fromGradient = [CAGradientLayer layer];
    fromGradient.frame = fromVC.view.bounds;
    fromGradient.colors = @[(id)[UIColor blackColor].CGColor,(id)[UIColor blackColor].CGColor];
    fromGradient.startPoint = CGPointMake(0.0, 0.5);
    fromGradient.endPoint = CGPointMake(0.8, 0.5);
    UIView *fromShadow = [[UIView alloc] initWithFrame:fromVC.view.bounds];
    fromShadow.backgroundColor = [UIColor clearColor];
    [fromShadow.layer insertSublayer:fromGradient atIndex:1];
    fromShadow.alpha = 0.0;
    [tempV addSubview:fromShadow];
    CAGradientLayer *toGradient = [CAGradientLayer layer];
    toGradient.frame = fromVC.view.bounds;
    toGradient.colors = @[(id)[UIColor blackColor].CGColor,(id)[UIColor blackColor].CGColor];
    toGradient.startPoint = CGPointMake(0.0, 0.5);
    toGradient.endPoint = CGPointMake(0.8, 0.5);
    UIView *toShadow = [[UIView alloc] initWithFrame:fromVC.view.bounds];
    toShadow.backgroundColor = [UIColor clearColor];
    [toShadow.layer insertSublayer:toGradient atIndex:1];
    toShadow.alpha = 1.0;
    [toVC.view addSubview:toShadow];
    //开始动画
    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        //沿Y轴旋转 逆时针180°
        tempV.layer.transform = CATransform3DMakeRotation(-M_PI_2, 0, 1, 0);
        //当前的由亮变暗 push的VC由暗变亮
        fromShadow.alpha = 1.0;
        toShadow.alpha = 0.0;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
        //动画取消的操作
        if ([transitionContext transitionWasCancelled]){
            [tempV removeFromSuperview];
            fromVC.view.hidden = NO;
        }
    }];
}

/**
 *  自定义pop动画
 */
- (void)doPopAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *containerV = [transitionContext containerView];
    UIView *tempV = containerV.subviews.lastObject;
    [containerV addSubview:toVC.view];
    //开始动画
    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        //临时图层恢复原状
        tempV.layer.transform = CATransform3DIdentity;
        fromVC.view.subviews.lastObject.alpha = 1.0;
        tempV.subviews.lastObject.alpha = 0.0;
    } completion:^(BOOL finished) {
        if ([transitionContext transitionWasCancelled]){
            [transitionContext completeTransition:NO];
        }else{
            [transitionContext completeTransition:YES];
            [tempV removeFromSuperview];
            toVC.view.hidden = NO;
        }
    }];
}

2.手势加上的效果如下:

![Uploading 翻页效果_161246.gif . . .]

DEMO FOUR:圆点扩散present效果

1.其它和上面相似,来看核心过渡的动画实现

- (void)presentAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UINavigationController *fromVC = (UINavigationController *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIView *containerV = [transitionContext containerView];
    PECircleSpreadController *temp = fromVC.viewControllers.lastObject;
    [containerV addSubview:toVC.view];
    //画两个圆路径
    UIBezierPath *startCircle = [UIBezierPath bezierPathWithOvalInRect:temp.buttonFrame];
    //始终用最大的x值和y值的平方根 来作为圆的半径 这样保证了圆点中心到最远的边的距离作为半径
    CGFloat x = MAX(temp.buttonFrame.origin.x, containerV.frame.size.width - temp.buttonFrame.origin.x);
    CGFloat y = MAX(temp.buttonFrame.origin.y, containerV.frame.size.height - temp.buttonFrame.origin.y);
    CGFloat radius = sqrtf(pow(x, 2) + pow(y, 2));
    //圆心 半径 开始角度 结束角度M_PI*2是360° 是否顺时针
    UIBezierPath *endCircle = [UIBezierPath bezierPathWithArcCenter:containerV.center radius:radius startAngle:0 endAngle:M_PI * 2 clockwise:YES];
    
    //创建CAShapLayer进行遮盖
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.path = endCircle.CGPath;
    //将maskLayer作为toVC的遮盖
    toVC.view.layer.mask = maskLayer;
    //创建路径动画
    CABasicAnimation *maskLayerAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
    //动画是添加到layer上的,所以必须为CGPath,再将CGPath桥接为OC对象
    maskLayerAnimation.fromValue = (__bridge id)(startCircle.CGPath);
    maskLayerAnimation.toValue = (__bridge id)(endCircle.CGPath);
    maskLayerAnimation.duration = [self transitionDuration:transitionContext];
    maskLayerAnimation.delegate = self;
    maskLayerAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];   //动画速度: 先慢 后慢 中间快
    [maskLayerAnimation setValue:transitionContext forKey:@"transitionContext"];
    [maskLayer addAnimation:maskLayerAnimation forKey:@"path"];    
}

- (void)dismissAnimation:(id<UIViewControllerContextTransitioning>)transitionContext
{
    PECircleSpreadPresentedController *fromVC = (PECircleSpreadPresentedController *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UINavigationController *toVC = (UINavigationController *)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    PECircleSpreadController *temp = toVC.viewControllers.lastObject;
    UIView *containerV = [transitionContext containerView];
    //画两个圆的路径
    CGFloat radius = sqrtf(pow(containerV.frame.size.height, 2) + pow(containerV.frame.size.width, 2))/2.0;
    UIBezierPath *startCircle = [UIBezierPath bezierPathWithArcCenter:containerV.center radius:radius startAngle:0 endAngle:M_PI*2 clockwise:YES];
    temp.buttonFrame = fromVC.presentButtonFrame;
    UIBezierPath *endCircle = [UIBezierPath bezierPathWithOvalInRect:temp.buttonFrame];
    //创建CAShapeLayer进行覆盖
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.fillColor = [UIColor greenColor].CGColor;
    maskLayer.path = endCircle.CGPath;
    fromVC.view.layer.mask = maskLayer;
    //创建路径动画
    CABasicAnimation *maskLayerAnimation = [CABasicAnimation animationWithKeyPath:@"path"];
    maskLayerAnimation.delegate = self;
    maskLayerAnimation.fromValue = (__bridge id)(startCircle.CGPath);
    maskLayerAnimation.toValue = (__bridge id)(endCircle.CGPath);
    maskLayerAnimation.duration = [self transitionDuration:transitionContext];
    maskLayerAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    [maskLayerAnimation setValue:transitionContext forKey:@"transitionContext"];
    [maskLayer addAnimation:maskLayerAnimation forKey:@"path"];
    
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{ 
    switch (_type) {
        case PECircleSpreadTransitionTypePresent:{
            id<UIViewControllerContextTransitioning> transitionContext = [anim valueForKey:@"transitionContext"];
            [transitionContext completeTransition:YES];
        }
            break;
        case PECircleSpreadTransitionTypeDismiss:{
            id<UIViewControllerContextTransitioning> transitionContext = [anim valueForKey:@"transitionContext"];
            [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
            if ([transitionContext transitionWasCancelled]) {
                //去掉遮挡层
                [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey].view.layer.mask = nil;
            }
        }
            break;
            
        default:
            break;
    }
}

注意:最后animationDidStop的代理方法中处理到动画的完成逻辑.
2.最后的效果如下:

小圆点扩散.gif
总结
1、关于：self.modalPresentationStyle = UIModalPresentationCustom;我查看了视图层级后发现，如果使用了Custom，在present动画完成的时候，presentingView也就是demo one中的vc1的view会从containerView中移除，只是移除，并未销毁，此时还被持有着(dismiss后还得回来呢！)，如果设置custom，那么present完成后，它一直都在containerView中，只是在最后面，所以需不需要设置custom可以看动画完成后的情况，是否还需要看见presentingViewController，但是记住如果没有设置custom，在disMiss的动画逻辑中，要把它加回containerView中，不然就不在咯~！
2、感觉写了好多东西，其实只要弄懂了转场的逻辑，其实就只需要写动画的逻辑就行了，其他东西都是固定的，而且苹果提供的这种控制转场的方式可充分解耦，除了写的手势过渡管理可以拿到任何地方使用，所有的动画过渡管理者都可以很轻松的复用到其他转场中，都不用分是何种转场，demo没有写标签控制器的转场，实现方法也是完全类似的，大家可以尝试一下，四个demo的github地址：自定义转场动画demo