自定义转场动画

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好久不用的东西,复习一下,先写一下转场动画吧O(∩_∩)O

直接开始,这篇博客分三部分,第一部分记述自定义modal动画,第二部记述自定义push动画,第三部分记一下常见动画的实现.

modal动画

下面简要写一下以modal的形式实现系统的push动画

主要步骤:
新建两个view controller,记做FromVC,ToVC;
在FromVC中,实现presentViewController:animated:completion,ToVC对象设置toVC.transitioningDelegate = self;,fromVC遵守协议UIViewControllerTransitioningDelegate;
看一下UIViewControllerTransitioningDelegate, 通过文档可以看到, UIViewControllerTransitioningDelegate主要要实现前两个方法来获取present和dismiss的动画对象

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 // Asks your delegate for the transition animator object to use when presenting a view controller.
- (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source;
 // Asks your delegate for the transition animator object to use when dismissing a view controller.
- (nullable id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed;
 // Asks your delegate for the interactive animator object to use when presenting a view controller.
- (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForPresentation:(id <UIViewControllerAnimatedTransitioning>)animator;
 // Asks your delegate for the interactive animator object to use when dismissing a view controller.
- (nullable id <UIViewControllerInteractiveTransitioning>)interactionControllerForDismissal:(id <UIViewControllerAnimatedTransitioning>)animator;
 // Asks your delegate for the custom presentation controller to use for managing the view hierarchy when presenting a view controller.
- (nullable UIPresentationController *)presentationControllerForPresentedViewController:(UIViewController *)presented presentingViewController:(UIViewController *)presenting sourceViewController:(UIViewController *)source NS_AVAILABLE_IOS(8_0);

而动画对象需要遵守UIViewControllerAnimatedTransitioning协议,看一下这个协议需要实现的方法:第一个方法返回的是动画执行的时间,第二个方法则是用于处理动画效果;

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  // This is used for percent driven interactive transitions, as well as for container controllers that have companion animations that might need to
  // synchronize with the main animation. 
- (NSTimeInterval)transitionDuration:(nullable id <UIViewControllerContextTransitioning>)transitionContext;
  // This method can only  be a nop if the transition is interactive and not a percentDriven interactive transition.
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext;

首先实现present动画,新建一个DHPresentAnimation类,继承自NSObject,并且实现UIViewControllerAnimatedTransitioning中的两个方法,代码如下:

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  // 动画执行的时间
- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContex
  {
    return 0.3;
  }
   // 自定义动画
- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext
 {
       // 获取目标VC
       UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
       // 获取最终要显示的VC的frame
       CGRect finalRect = [transitionContext finalFrameForViewController:toVC];
       // 设置目标VC的默认位置,这里定位在屏幕左侧
       toVC.view.frame = CGRectOffset(finalRect, -[[UIScreen mainScreen]bounds].size.width, 0);
       // 获取containerView,并将目标VC的view设置为它的子视图
       [[transitionContext containerView] addSubview:toVC.view];
       // 简单UIView动画,使toVC的view变换到最终要显示的位置和大小
       [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
           toVC.view.frame = finalRect;
       } completion:^(BOOL finished) {
       // 明确告诉上下文,结束动画
           [transitionContext completeTransition:YES];
       }];
 }

在FromVC中,实现UIViewControllerTransitioningDelegate协议方法

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- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source 
{
    // 返回present自定义动画对象
    return [[DHPresentAnimation alloc] init];
}

同理,实现dismiss动画,实现FromVC遵循协议中的另一个方法:
dismiss动画

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- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
 { 
   return 1.0;
 }
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
 { 
       UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
       UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; 
       CGRect initRect  = [transitionContext initialFrameForViewController:fromVC];   
       CGRect finalRect = CGRectOffset(initRect, -[[UIScreen mainScreen]bounds].size.width, 0);
       UIView *containerView = [transitionContext containerView];
       [containerView addSubview:toVC.view];
       [containerView sendSubviewToBack:toVC.view];
       [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
           fromVC.view.frame = finalRect;
       } completion:^(BOOL finished) {
           [transitionContext completeTransition:YES];
       }];
 }

协议方法:

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- (id<UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
  return [[DHDismissAnimation alloc] init];
}

最后command + R运行.

push动画

待续

常见动画的实现

待续