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
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
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
- (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
