如何在iOS8的自定义过渡动画中“传递”持久性标签？

我有一个自定义的视图控制器之间的过渡动画，并且我想要一个UILabel（或出现）在fromViewController和toViewController上都是相同的。如何在iOS8的自定义过渡动画中“传递”持久性标签？

我试过如下：

toViewController.nameLabel = fromViewController.nameLabel;

在下面的代码的情况下却得到了以下错误：

[UINavigationController nameLabel]: unrecognized selector sent to instance

我在做什么错？

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext { 
    // Grab the from and to view controllers from the context 
    HC_ExercisePageVC *fromViewController = (HC_ExercisePageVC *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; 
    HC_TimerVC *toViewController = (HC_TimerVC *)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; 

    if (self.presenting) { 

     fromViewController.view.userInteractionEnabled = NO; 

     [transitionContext.containerView addSubview:toViewController.view]; 

     CGRect startFrame = endFrame; 
     startFrame.origin.y += 75; 
     toViewController.movingViews.frame = startFrame; 

     toViewController.nameLabel = fromViewController.nameLabel; 

     [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{ 
      toViewController.movingViews.frame = endFrame; 
     } completion:^(BOOL finished) { 
      [transitionContext completeTransition:YES]; 
     }]; 
    } 
    else {

更新：继@Gavin的建议，我取代了代码：

// Grab the from and to view controllers from the context 
HC_ExercisePageVC *fromViewController = (HC_ExercisePageVC *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; 
UINavigationController *toViewControllerNavigation = (id)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; 
HC_TimerVC * toViewController = (HC_TimerVC *)toViewControllerNavigation.viewControllers.firstObject;

但是，当我这样做，我得到错误：

-[HC_TimerVC viewControllers]: unrecognized selector sent to instance

我总是挂上如何处理navcontrollers ...

来源

2015-03-02 Matt Miller

看起来像你的toViewController包含在UINavigationController内，因此它将返回作为目的地。

所以你需要从导航控制器抢HC_TimerVC：

- (void)animateTransition:(id <UIViewControllerContextTransitioning>)transitionContext { 
    // Grab the from and to view controllers from the context 
    HC_ExercisePageVC *fromViewController = (HC_ExercisePageVC *)[transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey]; 
    UINavigationController *toViewControllerNavigation = (id)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey]; 
    HC_TimerVC * toViewController = toViewControllerNavigation.viewControllers.firstObject; 
    ....

来源

2015-03-02 23:09:39

如何在iOS8的自定义过渡动画中“传递”持久性标签？

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