iOS自定义转场动画（push、pop动画）

2016-09-27 本文已影响4267人逆流丶而上

iOS7推出了新的转场动画API，以协议id<UIViewControllerInterativeTransition>、id<UIViewAnimatedTransitioning>方式开放给开发者，不同于代理、类别，这样更易于我们自定义动画，更加灵活。下面介绍一下自定义转场动画

仿酷狗push

push

要使用的协议

UIViewControllerInteractiveTransitioning 交互协议，主要在右滑返回时用到
UIViewControllerAnimatedTransitioning 动画协议，含有动画时间及转场上下文两个必须实现协议
UIViewControllerContextTransitioning 动画协议里边的协议之一，动画实现的主要部分
UIPrecentDrivenInteractiveTransition 用在交互协议，百分比控制当前动画进度。

自定义步骤

首先要实现navigation的代理，navigation有两个返回id类型的协议，实现这两个协议

第一个方法返回一个UIPercentDrivenInterativeTransition类型的对象即可，这个对象默认实现了UIPercentInterativeTransitioning协议，需要注意的是，这个返回值主要是用于交互动画，也就是右滑返回时需要用到，这里我在基类baseViewController定义了一个UIPercentDrivenInterativeTransition类型的属性。
- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController )navigationController
interactionControllerForAnimationController:(WTKBaseAnimation) animationControlle{
return animationControlle.interactivePopTransition;
}
第二个方法我自定义了一个遵循UIViewControllerAnimationTransitioning协议的类WTKBaseAnimation,
- (nullable id <UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController
animationControllerForOperation:(UINavigationControllerOperation)operation
fromViewController:(WTKBaseViewController *)fromVC
toViewController:(UIViewController *)toVC{
if (fromVC.interactivePopTransition)
{
WTKBaseAnimation *animation = [[WTKBaseAnimation alloc]initWithType:operation Duration:0.6 animateType:self.animationType];
animation.interactivePopTransition = fromVC.interactivePopTransition;
return animation; //手势
}
else
{
WTKBaseAnimation *animation = [[WTKBaseAnimation alloc]initWithType:operation Duration:0.6 animateType:self.animationType];
return animation;//非手势
};}

第二个方法返回对象自定义如下

baseAnimation构建方法.png

也就是需要把navigation的代理方法中的参数都传过来。
在本类中，需要实现转场动画协议：
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext{
return self.duration;}

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext{
if (self.transitionType == UINavigationControllerOperationPush)
{
    [self push:transitionContext];
}
else if (self.transitionType == UINavigationControllerOperationPop)
{
    [self pop:transitionContext];
}}

[self push:transitionContext]; [self pop:transitionContext];在本类中并没有真正的实现，具体交给子类实现

Paste_Image.png

- (void)push:(id<UIViewControllerContextTransitioning>)transitionContext{}
- (void)pop:(id<UIViewControllerContextTransitioning>)transitionContext{}

下面介绍子类的具体实现，

push

|
<pre><code>- (void)push:(id<UIViewControllerContextTransitioning>)transitionContext {

UIViewController * fromVc   = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];

UIViewController * toVc     = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

NSTimeInterval duration     = [self transitionDuration:transitionContext];

CGRect bounds               = [[UIScreen mainScreen] bounds];

fromVc.view.hidden          = YES;

[[transitionContext containerView] addSubview:toVc.view];

[[toVc.navigationController.view superview] insertSubview:fromVc.snapshot belowSubview:toVc.navigationController.view];

toVc.navigationController.view.transform =

CGAffineTransformMakeTranslation(CGRectGetWidth(bounds), 0);

[UIView animateWithDuration:duration
                      delay:0
     usingSpringWithDamping:1.0
      initialSpringVelocity:0
                    options:UIViewAnimationOptionCurveLinear
                 animations:^{
                     fromVc.snapshot.transform = CGAffineTransformMakeTranslation(-CGRectGetWidth(bounds) * 0.3, 0);
                     toVc.navigationController.view.transform = CGAffineTransformMakeTranslation(0, 0);
                 }
                 completion:^(BOOL finished) {
                     fromVc.view.hidden = NO;
                     [fromVc.snapshot removeFromSuperview];
                     [transitionContext completeTransition:YES];
}];
}

</code></pre>
其中fromVC与toVC、为函数参数transitionContext协议获得，duration调用父类方法获得，最终为navigation的代理方法中返回的时间，也可以自定义。fromVC为原来的ViewController，toVC为要push的VC
首先将fromVC的view隐藏，使用VC的snapshot代替，snapshot为viewController的截图，这里使用类别关联属性实现的。
[transitionContext containerView] 为容器，存转场需要的view，
分别将toVC.view及fromVC.snapshot添加到容器中，注意添加顺序、view存放的顺序。

下面将toVC移动到屏幕右边，这里使用的是改变transform，

使用UIView做动画，需要注意的是，使用usingSpringWithDamping的动画，关于这个动画不再多说。
UIView动画，需要把fromVC移动到左边（移动多少可自定），toVC移动到右边。
动画完成后，需要把原来隐藏的fromVC.view显示，添加到容器的view移除，当前显示的vc不需要移除。
** 最后需要调用转场完成方法** [transitionContext completeTransition:YES];

Pop

|

  - (void)pop:(id<UIViewControllerContextTransitioning>)transitionContext {

WTKBaseViewController * fromVc  = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];

UIViewController * toVc         = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

NSTimeInterval duration         = [self transitionDuration:transitionContext];

CGRect bounds                   = [[UIScreen mainScreen] bounds];

[fromVc.view addSubview:fromVc.snapshot];
fromVc.navigationController.navigationBar.hidden = YES;
fromVc.view.transform = CGAffineTransformIdentity;

toVc.view.hidden                = YES;
toVc.snapshot.transform         = CGAffineTransformMakeTranslation(-CGRectGetWidth(bounds) * 0.3, 0);

[[transitionContext containerView] addSubview:toVc.view];
[[transitionContext containerView] addSubview:toVc.snapshot];
[[transitionContext containerView] sendSubviewToBack:toVc.snapshot];

if (fromVc.interactivePopTransition)
{
    [UIView animateWithDuration:duration
                          delay:0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         fromVc.view.transform = CGAffineTransformMakeTranslation(CGRectGetWidth(bounds), 0.0);
                         toVc.snapshot.transform = CGAffineTransformIdentity;
                     }
                     completion:^(BOOL finished) {

                         toVc.navigationController.navigationBar.hidden = NO;
                         toVc.view.hidden = NO;

                         [fromVc.snapshot removeFromSuperview];
                         [toVc.snapshot removeFromSuperview];
                         fromVc.snapshot = nil;

                         if (![transitionContext transitionWasCancelled]) {
                             toVc.snapshot = nil;
                         }

                         [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
                     }];

}
else
{
    [UIView animateWithDuration:duration
                          delay:0
         usingSpringWithDamping:1
          initialSpringVelocity:0
                        options:UIViewAnimationOptionCurveLinear
                     animations:^{
                         fromVc.view.transform = CGAffineTransformMakeTranslation(CGRectGetWidth(bounds), 0.0);
                         toVc.snapshot.transform = CGAffineTransformIdentity;
                     }
                     completion:^(BOOL finished) {

                         toVc.navigationController.navigationBar.hidden = NO;
                         toVc.view.hidden = NO;

                         [fromVc.snapshot removeFromSuperview];
                         [toVc.snapshot removeFromSuperview];
                         fromVc.snapshot = nil;

                         if (![transitionContext transitionWasCancelled]) {
                             toVc.snapshot = nil;
                         }

                         [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
                     }];
}}

pop方法与push类似，不再多说，需要注意的是** 一定要区分手势和非手势 **，也就是如果点击按钮返回，需要使用usingSpringWithDamping动画，右滑返回不使用这个。
判断方式fromVc.interactivePopTransition，这个为在基类baseViewController里边自定义的一个UIPercentDrivenInterativeTransition类型的属性，也就是navigation代理方法- (nullable id <UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(WTKBaseAnimation*) animationControlle的返回值。

在baseViewController中添加手势:UIPanGestureRecognizer,添加到self.view上面，viewDidLoad中如下：

if (self.navigationController && self != self.navigationController.viewControllers.firstObject)
{
    UIPanGestureRecognizer *popRecognizer = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePopRecognizer:)];
    [self.view addGestureRecognizer:popRecognizer];
    popRecognizer.delegate = self;
}

在手势方法中创建UIPercentInterativeTransition，在拖动过程中，用这个实例变量调用updateInteractiveTransition方法，代码如下

- (void)handlePopRecognizer:(UIPanGestureRecognizer *)recognizer{
CGFloat progress = [recognizer translationInView:self.view].x / CGRectGetWidth(self.view.frame);
progress = MIN(1.0, MAX(0.0, progress));
NSLog(@"progress---%.2f",progress);
if (recognizer.state == UIGestureRecognizerStateBegan)
{
    self.interactivePopTransition = [[UIPercentDrivenInteractiveTransition alloc]init];
    [self.navigationController popViewControllerAnimated:YES];
}
else if (recognizer.state == UIGestureRecognizerStateChanged)
{
    [self.interactivePopTransition updateInteractiveTransition:progress];
}
else if (recognizer.state == UIGestureRecognizerStateEnded || recognizer.state == UIGestureRecognizerStateCancelled)
{
    if (progress > 0.25)
    {
        [self.interactivePopTransition finishInteractiveTransition];
    }
    else
    {
        [self.interactivePopTransition cancelInteractiveTransition];
    }
    self.interactivePopTransition = nil;
}}

上面定义的progress，为了记录滑动的百分比，随时更新interactivePopTransition 当手势结束,根据progress判断当前是否可以pop回来，这里是以0.25为标准。

代码连接 git连接

iOS自定义转场动画（push、pop动画）

要使用的协议

自定义步骤

push

Pop

|

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