iOS 自定义转场动画浅谈

代码地址如下：
http://www.demodashi.com/demo/11612.html

路漫漫其修远兮，吾将上下而求索

前记

想研究自定义转场动画很久了，时间就像海绵，挤一挤还是有的，花了差不多有10天的时间，终于对转场动画了解了一点。自从iOS 7以后，我们就可以自定义转场动画，实现我们想要的效果，在这之前，我们先来看一张图，大概了解下，需要知道些什么

相关类联系图

相信各位看官也差不多看完这张图了，下面我们就来简单了解下其中的类和相关的函数

说到转场动画，其实无非就是我们常用的push pop present dismiss四种动画，其中前面两个是成对使用，后面两个成对使用，我们先看看push这组在自定义转场动画中所涉及到的类

由于push动画组需要配合navigationController来使用，所以上图中的UINavigationControllerDelegate肯定是我们需要的类

UINavigationControllerDelegate

先来看看其中需要用到的函数

- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationControllerinteractionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationControlleranimationControllerForOperation:(UINavigationControllerOperation)operationfromViewController:(UIViewController *)fromVCtoViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);

第一个函数的返回值是一个id <UIViewControllerInteractiveTransitioning>值
第二个函数返回的值是一个id <UIViewControllerAnimatedTransitioning>值
那么我们就先从这两个返回值入手，来看下两个函数的作用

UIViewControllerInteractiveTransitioning 、UIPercentDrivenInteractiveTransition

这两个类又是干什么的呢？UIPercentDrivenInteractiveTransition遵守协议UIViewControllerInteractiveTransitioning,通过查阅资料了解到，UIPercentDrivenInteractiveTransition这个类的对象会根据我们的手势，来决定我们的自定义过渡的完成度，也就是这两个其实是和手势交互相关联的，自然而然我们就想到了iOS 7引进的侧滑手势，对，就是侧滑手势，说到这里，我就顺带介绍一个类，UIScreenEdgePanGestureRecognizer，手势侧滑的类，具体怎么使用，后面我会陆续讲到。

涉及函数

//更新进度
- (void)updateInteractiveTransition:(CGFloat)percentComplete;
//取消转场 回到转场前的效果
- (void)cancelInteractiveTransition;
//完成转场
- (void)finishInteractiveTransition;

UIViewControllerAnimatedTransitioning

在这个类中，我们又看到了两个函数

//转场时间
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

其中又涉及到一个新的类UIViewControllerContextTransitioning，那么这个又是干什么的呢？我们等下再来了解，先来谈谈第一个函数transitionDuration，从返回值我们可以猜测出这是和时间有关的，没错，这就是我们自定义转场动画所需要的时间
那么下面我们就来看看UIViewControllerContextTransitioning

UIViewControllerContextTransitioning

这个类就是我们自定义转场动画所需要的核心，即转场动画的上下文，定义了转场时需要的元素，比如在转场过程中所参与的视图控制器和视图的相关属性

//转场动画的容器
@property(nonatomic, readonly) UIView *containerView;
//通过对应的`key`可以得到我们需要的`vc`
- (UIViewController *)viewControllerForKey:(UITransitionContextViewControllerKey)key
//转场动画完成时候调用，必须调用，否则在进行其他转场没有任何效果
- (void)completeTransition:(BOOL)didComplete

看到这里，我们现在再去看UINavigationControllerDelegate中的两个函数和UIViewControllerAnimatedTransitioning中的animateTransition函数，就能完全理解了

//主要用于手势交互转场 for push or pop
- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationControllerinteractionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);//非手势交互转场 for push or pop
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationControlleranimationControllerForOperation:(UINavigationControllerOperation)operationfromViewController:(UIViewController *)fromVCtoViewController:(UIViewController *)toVC  NS_AVAILABLE_IOS(7_0);//实现转场动画 通过transitionContext
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

到此，我们还有一个类没有了解，那就是UIViewControllerTransitioningDelegate有了前面的分析，我们可以很好的理解

UIViewControllerTransitioningDelegate

主要是针对present和dismiss动画的转场

//非手势转场交互 for present
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
//非手势转场交互 for dismiss
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
//手势交互 for dismiss
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator
//手势交互 for present
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)animator

基本定义和概览我们差不多应该有了一定的了解，正如上图中的简单描述。

了解性的东西说了这么多，下面我们就来点实际性的东西，除了第一张开门那种自定义动画，再来几个比较常用的动画

这些动画都比较简单，相信许多大神都很清楚，还望见谅，下面我就对每一种进行分析分析，在分析动画之前，先来看看怎么将上面的各个类进行封装起来，使用更方便，这里不得不感谢很久之前看到的一篇文章，从他的文章中收获非常大。

在学习转场动画的时候，虽然对所有类的关系有了一定了解，但是封装的时候，完全没有想到还有这么好的思路，确实是学习了。下面我们就一起来看看封装思路。

封装思路

1. 新建一个综合管理转场动画的类

作用：主要是管理转场所需要的一些设置，诸如转场时间和转场的实现（主要是在子类中进行实现，分离开来），用户在自定义转场动画的时候，只需要继承该类并重写父类方法就可以
类名：GLTransitionManager，需要准守的协议有<UINavigationControllerDelegate,UIViewControllerTransitioningDelegate>
通过这样，就可以将present和push动画相关的操作在该类中进行管理
GLTransitionManager.h中具体方法

@interface GLTransitionManager : NSObject<UINavigationControllerDelegate,UIViewControllerTransitioningDelegate>/**转场动画的时间 默认为0.5s*/
@property (nonatomic,assign) NSTimeInterval duration;/**入场动画  @param contextTransition 实现动画*/
- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition;/**退场动画 @param contextTransition 实现动画*/
- (void)setBackAnimation:(id<UIViewControllerContextTransitioning>)contextTransition;

相信大家也看到了在入场和退场动画中都有(id<UIViewControllerContextTransitioning>) contextTransition这么一个参数，通过该参数，我们可以获取转场动画的相关vc和其他信息，进行转场动画的实现，即我们在自定义转场动画的时候，只需要重写该两个方法就可以，通过contextTransition来实现动画，而<UIViewControllerContextTransitioning>又在UIViewControllerAnimatedTransitioning协议的方法- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext中涉及到，于是我又新建了一个准守协议UIViewControllerAnimatedTransitioning的类GLTransitionAnimation，也就是下面我们将的类

2.转场动画配置及实现类

作用：虽然是配置和实现类，但是在该类中并没有进行实现，这里也正是之前那个博主的高明之处，至少我是这么认为的。在该类中，我们用block的传值方法将其传入到我们的管理类中，也就是GLTransitionManager

GLTransitionAnimation.h文件

/**GLTransitionAnimation 块 @param contextTransition 将满足UIViewControllerContextTransitioning协议的对象传到管理内 在管理类对动画统一实现*/
typedef void(^GLTransitionAnimationBlock)(id <UIViewControllerContextTransitioning> contextTransition);@interface GLTransitionAnimation : NSObject<UIViewControllerAnimatedTransitioning>@property (nonatomic,copy) GLTransitionAnimationBlock animationBlock;/**初始化方法 @param duration 转场时间
 @return 返回*/
- (id)initWithDuration:(NSTimeInterval)duration;

GLTransitionAnimation.m文件比较简单，这里就先不详说，我们先回到管理类中，来看看怎么使用

GLTransitionManager.m文件，
在此种定义两个属性

/**入场动画*/
@property (nonatomic,strong) GLTransitionAnimation *toTransitionAnimation;/**退场动画*/
@property (nonatomic,strong) GLTransitionAnimation *backTransitionAnimation;

实现方法

#pragma mark == 懒加载
- (GLTransitionAnimation *)toTransitionAnimation
{if (nil == _toTransitionAnimation) {__weak typeof(self) weakSelf = self;_toTransitionAnimation = [[GLTransitionAnimation alloc] initWithDuration:self.duration ];_toTransitionAnimation.animationBlock = ^(id<UIViewControllerContextTransitioning> contextTransition){[weakSelf setToAnimation:contextTransition];};}return _toTransitionAnimation;
}- (GLTransitionAnimation *)backTransitionAnimation
{if (nil == _backTransitionAnimation) {__weak typeof(self) weakSelf = self;_backTransitionAnimation = [[GLTransitionAnimation alloc] initWithDuration:self.duration];_backTransitionAnimation.animationBlock = ^(id<UIViewControllerContextTransitioning> contextTransition){[weakSelf setBackAnimation:contextTransition];};}return _backTransitionAnimation;
}

通过上面这一方法，我们就很好的将关键参数和对外接口联系起来了。这样我们就只需要在setToAnimation和setBackAnimation进行转场动画的具体实现即可。
当然这里还有一个小问题，相信各位也发现了，就是为什么将属性定义在了.m文件里呢？是的，这里确实是定义在了.m文件中，其实就是为了更少的暴露不需要的。

搞定这个之后，我们在来看看，在上面时候，调用该属性呢？
下面我们就来看具体使用的地方

//非手势转场交互 for present
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source{return self.toTransitionAnimation;
}//非手势转场交互 for dismiss
- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed{return self.backTransitionAnimation;
}//================
//非手势转场交互 for push or pop
/*****注释:通过 fromVC 和 toVC 我们可以在此设置需要自定义动画的类 *****/
- (id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationControlleranimationControllerForOperation:(UINavigationControllerOperation)operationfromViewController:(UIViewController *)fromVCtoViewController:(UIViewController *)toVC
{_operation = operation;if (operation == UINavigationControllerOperationPush){return self.toTransitionAnimation;}else if (operation == UINavigationControllerOperationPop){return self.backTransitionAnimation;}else{return nil;}
}

在这两个地方使用后，我们差不多就完成了一半了，那还一部分呢？那就是我们的手势滑动，下面我们就来看看手势滑动。

3.手势交互管理类

作用：主要通过侧滑手势来管理交互，在iOS 7后引入新的类UIPercentDrivenInteractiveTransition，该类的对象会根据我们的手势，来决定我们的自定义过渡的完成度，所以此次我采用继承的方式，然后在继承的类中加入滑动手势类，这里加入的是侧滑手势类UIScreenEdgePanGestureRecognizer，这个类也就是我定义的GLInteractiveTransition类

GLInteractiveTransition.h文件


/**手势的方向枚举- GLPanEdgeTop:屏幕上方- GLPanEdgeLeft:屏幕左侧- GLPanEdgeBottom: 屏幕下方- GLPanEdgeRight: 屏幕右方*/
typedef NS_ENUM(NSInteger,GLEdgePanGestureDirection) {GLPanEdgeTop    = 0,GLPanEdgeLeft,GLPanEdgeBottom,GLPanEdgeRight
};///**
// 手势转场类型
//
// - GLInteractiveTransitionPush: push
// - GLInteractiveTransitionPop: pop
// - GLInteractiveTransitionPresent: present
// - GLInteractiveTransitionDismiss: dismiss
// */
//typedef NS_ENUM(NSInteger,GLInteractiveTransitionType) {//    GLInteractiveTransitionPush = 0,
//    GLInteractiveTransitionPop,
//    GLInteractiveTransitionPresent ,
//    GLInteractiveTransitionDismiss
//};@interface GLInteractiveTransition : UIPercentDrivenInteractiveTransition/**是否满足侧滑手势交互*/
@property (nonatomic,assign) BOOL isPanGestureInteration;/**转场时的操作 不用传参数的block*/
@property (nonatomic,copy) dispatch_block_t eventBlcok;/**添加侧滑手势 @param view 添加手势的view
 @param direction 手势的方向*/
- (void)addEdgePageGestureWithView:(UIView *)view direction:(GLEdgePanGestureDirection)direction;

在.h文件中，定义了两个属性，一个是用来判断是否需满足侧滑手势，这个在后面会讲到。另一个是用来在侧滑的时候执行所需要的转场的block，之前本来是没有加这个的，但是在后面使用的时候，由于想加侧滑的present和push效果，所以就加了一个。

下面看看.m文件滑动手势中的具体实现

- (void)handlePopRecognizer:(UIPanGestureRecognizer*)recognizer {// 计算用户手指划了多远CGFloat progress = fabs([recognizer translationInView:self.gestureView].x) / (self.gestureView.bounds.size.width * 1.0);progress = MIN(1.0, MAX(0.0, progress));switch (recognizer.state) {case UIGestureRecognizerStateBegan:{_isPanGestureInteration = YES;if (self.eventBlcok) {self.eventBlcok();}// 创建过渡对象，弹出viewController
//
//            UIViewController *fromVc = [self gl_viewController];
//
//            switch (self.transitionType) {//                case GLInteractiveTransitionPush:
//                {//
//                }
//                    break;
//                case GLInteractiveTransitionPop:
//                {//                    if (fromVc.navigationController) {//                        [fromVc.navigationController popViewControllerAnimated:YES];
//                    }
//                }
//                    break;
//                case GLInteractiveTransitionPresent:
//                {//
//                }
//                    break;
//                case GLInteractiveTransitionDismiss:
//                {//                    [fromVc dismissViewControllerAnimated:YES completion:nil];
//                }
//                    break;
//                default:
//                    break;
//            }break;}case UIGestureRecognizerStateChanged:{// 更新 interactive transition 的进度[self updateInteractiveTransition:progress];break;}case UIGestureRecognizerStateEnded:case UIGestureRecognizerStateCancelled:{
//            NSLog(@" 打印信息:%f",progress);// 完成或者取消过渡if (progress > 0.5) {[self finishInteractiveTransition];}else {[self cancelInteractiveTransition];}_isPanGestureInteration = NO;break;}default:break;}
}

手势交互管理类的核心代码差不多就这么多，下面我们看看怎么使用

4.`UIViewController + GLTransition`

为了和系统的转场动画的函数区分开来，这里我新建了一个UIViewController的category类UIViewController + GLTransition，在其中定义了四个函数，分别如下

/**push动画 @param viewController 被push viewController
 @param transitionManager 控制类*/
- (void)gl_pushViewControler:(UIViewController *)viewController withAnimation:(GLTransitionManager*)transitionManager;/**present动画 @param viewController 被present viewController
 @param transitionManager 控制类*/
- (void)gl_presentViewControler:(UIViewController *)viewController withAnimation:(GLTransitionManager*)transitionManager;/**注册入场手势 @param direction 方向
 @param blcok 手势转场触发的点击事件*/
- (void)gl_registerToInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok;/**注册返回手势 @param direction 侧滑方向
 @param blcok 手势转场触发的点击事件*/
- (void)gl_registerBackInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok;

下面我们看看具体实现
UIViewController (GLTransition).m文件

- (void)gl_pushViewControler:(UIViewController *)viewController withAnimation:(GLTransitionManager *)transitionManager
{if (!viewController) {return;}if (!transitionManager) {return;}if (self.navigationController) {self.navigationController.delegate = transitionManager;GLInteractiveTransition *toInteractiveTransition = objc_getAssociatedObject(self, &kToAnimationKey);if (toInteractiveTransition) {[transitionManager setValue:toInteractiveTransition forKey:@"toInteractiveTransition"];}objc_setAssociatedObject(viewController, &kAnimationKey, transitionManager, OBJC_ASSOCIATION_RETAIN_NONATOMIC);[self.navigationController pushViewController:viewController animated:YES];}
}- (void)gl_presentViewControler:(UIViewController *)viewController withAnimation:(GLTransitionManager *)transitionManager
{if (!viewController) {return;}if (!transitionManager) {return;}//present 动画代理 被执行动画的vc设置代理viewController.transitioningDelegate = transitionManager;GLInteractiveTransition *toInteractiveTransition = objc_getAssociatedObject(self, &kToAnimationKey);if (toInteractiveTransition) {[transitionManager setValue:toInteractiveTransition forKey:@"toInteractiveTransition"];}objc_setAssociatedObject(viewController, &kAnimationKey, transitionManager, OBJC_ASSOCIATION_RETAIN_NONATOMIC);[self presentViewController:viewController animated:YES completion:nil];
}- (void)gl_registerToInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok
{GLInteractiveTransition *interactiveTransition = [[GLInteractiveTransition alloc] init];interactiveTransition.eventBlcok = blcok;[interactiveTransition addEdgePageGestureWithView:self.view direction:direction];objc_setAssociatedObject(self, &kToAnimationKey, interactiveTransition, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}- (void)gl_registerBackInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok
{GLInteractiveTransition *interactiveTransition = [[GLInteractiveTransition alloc] init];interactiveTransition.eventBlcok = blcok;[interactiveTransition addEdgePageGestureWithView:self.view direction:direction];//判读是否需要返回 然后添加侧滑GLTransitionManager *animator = objc_getAssociatedObject(self, &kAnimationKey);if (animator){//用kvc的模式  给 animator的backInteractiveTransition 退场赋值[animator setValue:interactiveTransition forKey:@"backInteractiveTransition"];}
}

在push和present中，有几个需要注意的地方
1、self.navigationController.delegate = transitionManager
2、viewController.transitioningDelegate = transitionManager
上面两个主要是将navigationController的代理和viewController的transitioningDelegate指向对象transitionManager，这个对象是准守了<UINavigationControllerDelegate,UIViewControllerTransitioningDelegate>两个协议的，这样我们就能够在push和present的时候，简单的去调协议方法。

3、设置手势交互转场

        GLInteractiveTransition *toInteractiveTransition = objc_getAssociatedObject(self, &kToAnimationKey);if (toInteractiveTransition) {[transitionManager setValue:toInteractiveTransition forKey:@"toInteractiveTransition"];}

在push和present方法中，都有这样的代码，这里为了减少不必要的暴露，在GLTransitionManager.m文件中，我还定义了两个属性

/**入场手势*/
@property (nonatomic,strong) GLInteractiveTransition *toInteractiveTransition;/**退场手势*/
@property (nonatomic,strong) GLInteractiveTransition *backInteractiveTransition;

并且通过kvc的方式对其进行赋值，当转场动画进行的时候，会先去调用非转场动画的方法，比如push的时候，会先调用

- (id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationControlleranimationControllerForOperation:(UINavigationControllerOperation)operationfromViewController:(UIViewController *)fromVCtoViewController:(UIViewController *)toVC

然后再调用手势交互

//手势交互 for push or pop
- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController

这个时候，我们就需要加一个判断，也就是通过GLInteractiveTransition类中的是否满足侧滑手势交互isPanGestureInteration这个属性来判断，前面在侧滑手势刚刚进行的时候，就对其进行了赋值，并设置为yes，对应的实现代码就是

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController
{if (_operation == UINavigationControllerOperationPush) {return self.toInteractiveTransition.isPanGestureInteration ? self.toInteractiveTransition:nil;}else{return self.backInteractiveTransition.isPanGestureInteration ? self.backInteractiveTransition:nil;}
}

如果返回的为nil，那么就不会去调用手势交互类，否则则会调用。同理，present的时候也是一样
所以就有了下面的代码

//手势交互 for dismiss
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id<UIViewControllerAnimatedTransitioning>)animator{return self.backInteractiveTransition.isPanGestureInteration ? self.backInteractiveTransition:nil;
}//手势交互 for present
- (id<UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id<UIViewControllerAnimatedTransitioning>)animator{return self.toInteractiveTransition.isPanGestureInteration ? self.toInteractiveTransition:nil;
}

在UIViewController + GLTransition中的push和present函数中，还有一个需要注意的地方，那就是

objc_setAssociatedObject(viewController, &kAnimationKey, transitionManager, OBJC_ASSOCIATION_RETAIN_NONATOMIC);

这里通过runtime的方式给vc设置了一个属性值，为什么这么做呢？因为在arc下，如果我们在使用GLTransitionManager的时候去创建一个对象而非vc的属性，那么在push的时候GLTransitionManager这个对象就会被系统释放掉，这样我们后面所有有关转场的操作就不能再实现了，或许我们可以给vc建一个base类，然后添加一个GLTransitionManager对象的属性，但是这样或许有点复杂，所有这里就这样处理了。

在UIViewController + GLTransition中还有两个函数的实现，其原理，我相信大家应该都能看明白了，就不再详细说明了

- (void)gl_registerToInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok
{GLInteractiveTransition *interactiveTransition = [[GLInteractiveTransition alloc] init];interactiveTransition.eventBlcok = blcok;[interactiveTransition addEdgePageGestureWithView:self.view direction:direction];objc_setAssociatedObject(self, &kToAnimationKey, interactiveTransition, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}- (void)gl_registerBackInteractiveTransitionWithDirection:(GLEdgePanGestureDirection)direction eventBlcok:(dispatch_block_t)blcok
{GLInteractiveTransition *interactiveTransition = [[GLInteractiveTransition alloc] init];interactiveTransition.eventBlcok = blcok;[interactiveTransition addEdgePageGestureWithView:self.view direction:direction];//判读是否需要返回 然后添加侧滑GLTransitionManager *animator = objc_getAssociatedObject(self, &kAnimationKey);if (animator){//用kvc的模式  给 animator的backInteractiveTransition 退场赋值[animator setValue:interactiveTransition forKey:@"backInteractiveTransition"];}
}

整个封装的思路差不多到这里就完了，希望对大家有用

文章有点长，希望大家能够理解，因为后面还有。。。。

几个动画的具体实现

1、开门动画

由于我们已经有了基类“，所以当我们需要实现什么动画的时候，只需要集成该类就可以了

针对开门动画我新建了下面这么一个类GLTransitionManager

@interface GLOpenDoorAnimation : GLTransitionManager@end

然后在重新父类的方法

- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition

具体实现
1、根据id<UIViewControllerContextTransitioning>对象先得到几个关键值，目标vc和当前vc和容器containerView

    //获取目标动画的VCUIViewController *toVc = [contextTransition viewControllerForKey:UITransitionContextToViewControllerKey];UIViewController *fromVc = [contextTransition viewControllerForKey:UITransitionContextFromViewControllerKey];UIView *containerView = [contextTransition containerView];

2、由于是开门动画，所以其过程大概是这样的：当前vc逐渐缩小，目标vc慢慢从屏幕两边移到中间，但是我们又不能把目标vc的view分成两个部分，所以这里我们可以利用截图，来给用户造成一个假象。先截两个图，然后分别让其坐标居于屏幕外，然后用动画让其慢慢移动到屏幕中间，动画完成的时候，移除当前两个截图。这里有个小问题，那就是当前vc的缩放，虽然我们能够使其缩小，但是这样，如果涉及到侧滑手势的话，问题就来了。因为view的宽发生了变化，这样我们根据宽度来计算滑动的距离，从而更新转场动画的时候就会出现问题，导致

- (void)handlePopRecognizer:(UIPanGestureRecognizer*)recognizer {// 计算用户手指划了多远CGFloat progress = fabs([recognizer translationInView:self.gestureView].x) / (self.gestureView.bounds.size.width * 1.0);progress = MIN(1.0, MAX(0.0, progress));

中的progress出现问题。所以这里也就采用了截图的方式，对该截图进行缩放，而不去修改vc的view。

下面看下核心代码

- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition
{//获取目标动画的VCUIViewController *toVc = [contextTransition viewControllerForKey:UITransitionContextToViewControllerKey];UIViewController *fromVc = [contextTransition viewControllerForKey:UITransitionContextFromViewControllerKey];UIView *containerView = [contextTransition containerView];UIView *fromView = fromVc.view;UIView *toView = toVc.view;//截图UIView *toView_snapView = [toView snapshotViewAfterScreenUpdates:YES];CGRect left_frame = CGRectMake(0, 0, CGRectGetWidth(fromView.frame) / 2.0, CGRectGetHeight(fromView.frame));CGRect right_frame = CGRectMake(CGRectGetWidth(fromView.frame) / 2.0, 0, CGRectGetWidth(fromView.frame) / 2.0, CGRectGetHeight(fromView.frame));UIView *from_left_snapView = [fromView resizableSnapshotViewFromRect:left_frameafterScreenUpdates:NOwithCapInsets:UIEdgeInsetsZero];UIView *from_right_snapView = [fromView resizableSnapshotViewFromRect:right_frameafterScreenUpdates:NOwithCapInsets:UIEdgeInsetsZero];toView_snapView.layer.transform = CATransform3DMakeScale(0.7, 0.7, 1);from_left_snapView.frame = left_frame;from_right_snapView.frame = right_frame;//将截图添加到 containerView 上[containerView addSubview:toView_snapView];[containerView addSubview:from_left_snapView];[containerView addSubview:from_right_snapView];fromView.hidden = YES;[UIView animateWithDuration:self.duration delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{//左移from_left_snapView.frame = CGRectOffset(from_left_snapView.frame, -from_left_snapView.frame.size.width, 0);//右移from_right_snapView.frame = CGRectOffset(from_right_snapView.frame, from_right_snapView.frame.size.width, 0);toView_snapView.layer.transform = CATransform3DIdentity;} completion:^(BOOL finished) {fromView.hidden = NO;[from_left_snapView removeFromSuperview];[from_right_snapView removeFromSuperview];[toView_snapView removeFromSuperview];if ([contextTransition transitionWasCancelled]) {[containerView addSubview:fromView];} else {[containerView addSubview:toView];}[contextTransition completeTransition:![contextTransition transitionWasCancelled]];}];
}

setBackAnimation动画和上面的大同小异，就不再详细说明，文章后面有demo地址，大家可以看看。

2、圆圈逐渐放大转场动画

在做动画之前，我们先要了解其大概原理
这里我简单的做了个草图

小圆和大圆分别表示动画前和动画后
这里我们采用的是UIBezierPath + mask + CAShapeLayer的策略对其进行实习

大家都知道，UIBezierPath可以画圆形，而CAShapeLayer又具备CGPathRef path属性，可以和UIBezierPath联系起来，而UIView又具备CALayer *mask属性，这样三者就这么巧妙的联系起来了。
在这里，我们使用CABasicAnimation动画，通过对其设置[CABasicAnimation animationWithKeyPath:@"path"]来让其执行我们想要的path路径动画
于是就有了下面的代码

- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition
{//获取目标动画的VCUIViewController *toVc = [contextTransition viewControllerForKey:UITransitionContextToViewControllerKey];UIView *containerView = [contextTransition containerView];[containerView addSubview:toVc.view];//创建UIBezierPath路径 作为后面动画的起始路径UIBezierPath *startPath = [UIBezierPath bezierPathWithArcCenter:self.centerPoint radius:self.radius startAngle:0 endAngle:2*M_PI clockwise:YES];//创建结束UIBezierPath//首先我们需要得到后面路径的半径  半径应该是距四个角最远的距离CGFloat x = self.centerPoint.x;CGFloat y = self.centerPoint.y;//取出其中距屏幕最远的距离 来求围城矩形的对角线 即我们所需要的半径CGFloat radius_x = MAX(x, containerView.frame.size.width - x);CGFloat radius_y = MAX(y, containerView.frame.size.height - y);//补充下 sqrtf求平方根   double pow(double x, double y); 求 x 的 y 次幂（次方）//通过勾股定理算出半径CGFloat endRadius = sqrtf(pow(radius_x, 2) + pow(radius_y, 2));UIBezierPath *endPath = [UIBezierPath bezierPathWithArcCenter:self.centerPoint radius:endRadius startAngle:0 endAngle:2*M_PI clockwise:YES];//    self.endPath = endPath;//创建CAShapeLayer 用以后面的动画CAShapeLayer *shapeLayer = [CAShapeLayer layer];shapeLayer.path = endPath.CGPath;toVc.view.layer.mask = shapeLayer;CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];animation.fromValue = (__bridge id _Nullable)(startPath.CGPath);animation.duration = self.duration;animation.delegate = (id)self;
//    animation.removedOnCompletion = NO;//执行后移除动画//保存contextTransition  后面动画结束的时候调用[animation setValue:contextTransition forKey:@"pathContextTransition"];[shapeLayer addAnimation:animation forKey:nil];self.maskShapeLayer = shapeLayer;
}

由于代码中有比较详细的说明，所以这里就不再详细说明，setBackAnimation也大同小异

3、圆圈和目标vc共同缩放转场动画

这个比较简单，主要是利用UIView的缩放进行的，由于目标vc的上角和圆是相切的，所以，这里我们可以先假设目标vc处于正常状态，然后再跟进小圆的中心，画一个大圆，让其和目标vc一起缩放就是。这里留了一个缺陷，那就是不支持侧滑，因为我是用目标vc进行缩放的，而没有截图，大家可以试试。
其实现大概为

- (CGRect)frameToCircle:(CGPoint)centerPoint size:(CGSize)size
{CGFloat radius_x = fmax(centerPoint.x, size.width - centerPoint.x);CGFloat radius_y = fmax(centerPoint.y, size.height - centerPoint.y);CGFloat endRadius = 2 * sqrtf(pow(radius_x, 2) + pow(radius_y, 2));CGRect rect = {CGPointZero,CGSizeMake(endRadius, endRadius)};return rect;
}- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition
{//获取目标动画的VCUIViewController *toVc = [contextTransition viewControllerForKey:UITransitionContextToViewControllerKey];UIView *containerView = [contextTransition containerView];//    [toVc beginAppearanceTransition:YES animated:YES];CGPoint center = toVc.view.center;CGRect rect = [self frameToCircle:self.centerPoint size:toVc.view.bounds.size];UIView *backView = [[UIView alloc] initWithFrame:rect];backView.backgroundColor = UICOLOR_FROM_RGB_OxFF(0xFFA500);backView.center = self.centerPoint;backView.layer.cornerRadius = backView.frame.size.height / 2.0;backView.transform = CGAffineTransformMakeScale(0.01, 0.01);[containerView addSubview:backView];self.startView = backView;toVc.view.transform = CGAffineTransformMakeScale(0.01, 0.01);toVc.view.alpha = 0;toVc.view.center = self.centerPoint;[containerView addSubview:toVc.view];[UIView animateWithDuration:self.duration animations:^{backView.transform = CGAffineTransformIdentity;toVc.view.center = center;toVc.view.transform = CGAffineTransformIdentity;toVc.view.alpha = 1;} completion:^(BOOL finished) {[contextTransition completeTransition:!contextTransition.transitionWasCancelled];//        [toVc endAppearanceTransition];}];
}

setBackAnimation也大同小异，就不再说明

4、翻书效果

这个还是花了些时间，主要不在思想上，而是在翻书有个阴影效果哪里，等下我会讲到。先说说思路，主要还是通过截图来实现。首先需要截当前vc的部分，如果向左滑则截右边，向右则截左，然后还需要截目标vc的两部分图，分别加到containerView上，假如现在向左翻，那么就要将目标vc的左边截图加到containerView的左边并且隐藏起来，让其绕y轴旋转M_PI_2，就是直插屏幕的样子，那么目标vc的右边截图就需要放到当前vc的下面，这样当当前vc在滑动的时候，我们就能看到下面的图了。当当前vc绕y轴旋转-M_PI_2的时候，目标vc的左边截图显示出来，并恢复原状，完成整副动画。
需要注意的是，截图在绕y轴旋转的时候，因为我们的layer的默认anchorPoint为(0.5,0.5)，所以需要改变anchorPoint的只，否则就绕中心在旋转了。

说了这么多，还是看看核心代码吧

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; color: #3d71ff}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; color: #4dbf56}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; color: #00afca}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; color: #3d71ff; min-height: 16.0px}p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Menlo; color: #2337da}p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px 'PingFang SC'; color: #4dbf56}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #c2349b}span.s3 {font-variant-ligatures: no-common-ligatures; color: #00afca}span.s4 {font-variant-ligatures: no-common-ligatures; color: #3d71ff}span.s5 {font: 14.0px 'PingFang SC'; font-variant-ligatures: no-common-ligatures}span.s6 {font-variant-ligatures: no-common-ligatures; color: #4dbf56}span.s7 {font: 14.0px 'PingFang SC'; font-variant-ligatures: no-common-ligatures; color: #4dbf56}span.s8 {font: 14.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #2337da}span.s9 {font: 14.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #3d71ff}span.s10 {font: 14.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s11 {font-variant-ligatures: no-common-ligatures; color: #8b84cf}span.s12 {font-variant-ligatures: no-common-ligatures; color: #93c96a}span.s13 {font-variant-ligatures: no-common-ligatures; color: #d28f5a}- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition
{//获取目标动画的VCUIViewController *toVc = [contextTransition viewControllerForKey:UITransitionContextToViewControllerKey];UIViewController *fromVc = [contextTransition viewControllerForKey:UITransitionContextFromViewControllerKey];UIView *containerView = [contextTransition containerView];//m34 这个参数有点不好理解  为透视效果 我在http://www.jianshu.com/p/e8d1985dccec这里有讲//当Z轴上有变化的时候 我们所看到的透视效果 可以对比看看 当你改成-0.1的时候 就懂了CATransform3D transform = CATransform3DIdentity;transform.m34 = -0.002;[containerView.layer setSublayerTransform:transform];UIView *fromView = fromVc.view;UIView *toView = toVc.view;//截图//当前页面的右侧CGRect from_half_right_rect = CGRectMake(fromView.frame.size.width/2.0, 0, fromView.frame.size.width/2.0, fromView.frame.size.height);//目标页面的左侧CGRect to_half_left_rect = CGRectMake(0, 0, toView.frame.size.width/2.0, toView.frame.size.height);//目标页面的右侧CGRect to_half_right_rect = CGRectMake(toView.frame.size.width/2.0, 0, toView.frame.size.width/2.0, toView.frame.size.height);//截三张图 当前页面的右侧 目标页面的左和右UIView *fromRightSnapView = [fromView resizableSnapshotViewFromRect:from_half_right_rect afterScreenUpdates:NO withCapInsets:UIEdgeInsetsZero];UIView *toLeftSnapView = [toView resizableSnapshotViewFromRect:to_half_left_rect afterScreenUpdates:YES withCapInsets:UIEdgeInsetsZero];UIView *toRightSnapView = [toView resizableSnapshotViewFromRect:to_half_right_rect afterScreenUpdates:YES withCapInsets:UIEdgeInsetsZero];fromRightSnapView.frame = from_half_right_rect;toLeftSnapView.frame = to_half_left_rect;toRightSnapView.frame = to_half_right_rect;//重新设置anchorPoint  分别绕自己的最左和最右旋转fromRightSnapView.layer.position = CGPointMake(CGRectGetMinX(fromRightSnapView.frame), CGRectGetMinY(fromRightSnapView.frame) + CGRectGetHeight(fromRightSnapView.frame) * 0.5);fromRightSnapView.layer.anchorPoint = CGPointMake(0, 0.5);toLeftSnapView.layer.position = CGPointMake(CGRectGetMinX(toLeftSnapView.frame) + CGRectGetWidth(toLeftSnapView.frame), CGRectGetMinY(toLeftSnapView.frame) + CGRectGetHeight(toLeftSnapView.frame) * 0.5);toLeftSnapView.layer.anchorPoint = CGPointMake(1, 0.5);//添加阴影效果UIView *fromRightShadowView = [self addShadowView:fromRightSnapView startPoint:CGPointMake(0, 1) endPoint:CGPointMake(1, 1)];UIView *toLeftShaDowView = [self addShadowView:toLeftSnapView startPoint:CGPointMake(1, 1) endPoint:CGPointMake(0, 1)];//添加视图  注意顺序[containerView insertSubview:toView atIndex:0];[containerView addSubview:toLeftSnapView];[containerView addSubview:toRightSnapView];[containerView addSubview:fromRightSnapView];toLeftSnapView.hidden = YES;//先旋转到最中间的位置toLeftSnapView.layer.transform = CATransform3DMakeRotation(M_PI_2, 0, 1, 0);//StartTime 和 relativeDuration 均为百分百[UIView animateKeyframesWithDuration:self.duration delay:0 options:UIViewKeyframeAnimationOptionCalculationModeLinear animations:^{[UIView addKeyframeWithRelativeStartTime:0 relativeDuration:0.5 animations:^{fromRightSnapView.layer.transform = CATransform3DMakeRotation(-M_PI_2, 0, 1, 0);fromRightShadowView.alpha = 1.0;}];[UIView addKeyframeWithRelativeStartTime:0.5 relativeDuration:0.5 animations:^{toLeftSnapView.hidden = NO;toLeftSnapView.layer.transform = CATransform3DIdentity;toLeftShaDowView.alpha = 0.0;}];} completion:^(BOOL finished) {[toLeftSnapView removeFromSuperview];[toRightSnapView removeFromSuperview];[fromRightSnapView removeFromSuperview];[fromView removeFromSuperview];if ([contextTransition transitionWasCancelled]) {[containerView addSubview:fromView];}[contextTransition completeTransition:![contextTransition transitionWasCancelled]];}];//本来打算用基础动画来实现 但是由于需要保存几个变量 在动画完成的代理函数中用，所以就取消这个想法了
//    CABasicAnimation *fromRightAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.x"];
//    fromRightAnimation.duration = self.duration/2.0;
//    fromRightAnimation.beginTime = CACurrentMediaTime();
//    fromRightAnimation.toValue = @(-M_PI_2);
//    [fromRightSnapView.layer addAnimation:fromRightAnimation forKey:nil];
//
//
//    CABasicAnimation *toLeftAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.x"];
//    toLeftAnimation.beginTime = CACurrentMediaTime() + self.duration/2.0;
//    toLeftAnimation.fromValue = @(M_PI_2);
//    [toLeftAnimation setValue:contextTransition forKey:@"contextTransition"];
//    [toLeftSnapView.layer addAnimation:toLeftAnimation forKey:@"toLeftAnimation"];
}

项目文件截图：

写到这里，差不多转场动画我能够写的就到这里了，文章实在是有点长，不是故意为之，只是我想写的稍微详细点，对自己也是一个很好的提升。如果能帮到你，还请给个打赏，嘿嘿~
如果有什么不对的地方，还请多多指教，共同成长。
iOS 自定义转场动画浅谈

代码地址如下：
http://www.demodashi.com/demo/11612.html

注：本文著作权归作者，由demo大师发表，拒绝转载，转载需要作者授权