iOS 自定义转场动画
路漫漫其修远兮，吾将上下而求索
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
先来看看其中需要用到的函数
- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController
interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(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
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;
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
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 *)navigationController
interactionControllerForAnimationController:(id <UIViewControllerAnimatedTransitioning>) animationController NS_AVAILABLE_IOS(7_0);
//非手势交互转场 for push or pop
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(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
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。
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
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 *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(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。
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
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 *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(UIViewController *)fromVC
toViewController:(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。。。。
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VC
UIViewController *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VC
UIViewController *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_frame
afterScreenUpdates:NO
withCapInsets:UIEdgeInsetsZero];
UIView *from_right_snapView = [fromView resizableSnapshotViewFromRect:right_frame
afterScreenUpdates:NO
withCapInsets: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。
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
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VC
UIViewController *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
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VC
UIViewController *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
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
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- (void)setToAnimation:(id<UIViewControllerContextTransitioning>)contextTransition
{
//获取目标动画的VC
UIViewController *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"];
}
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star，嘿嘿~
下面就附上demo地址
如果有什么不对的地方，还请多多指教，共同成长。