在使用自定义UIViewController动画的动画后呈现的视图控制器消失

Question

我环顾四周寻找答案，并花了最后两个小时将我的头发拉到了最后。

我正在实现一个非常基本的自定义视图控制器转换动画，它只是放大呈现视图控制器，并在呈现的视图控制器中增长。它增加了淡入淡出效果（0到1 alpha，反之亦然）。

当呈现视图控制器时它可以正常工作，但是当解散时，它会将视图控制器全部重新填满屏幕，但随后它会莫名其妙地消失。在这些动画改变alpha值或隐藏值之后，我没有做任何事情，这几乎是一个新鲜的项目。我一直在开发iOS应用程序3年，所以我怀疑这可能是一个错误，除非有人能够找出我要出错的地方。

class FadeAndGrowAnimationController : NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate { 
func animationControllerForPresentedController(presented: UIViewController!, presentingController presenting: UIViewController!, sourceController source: UIViewController!) -> UIViewControllerAnimatedTransitioning! { 
    return self 
} 

func animationControllerForDismissedController(dismissed: UIViewController!) -> UIViewControllerAnimatedTransitioning! { 
    return self 
} 

func transitionDuration(transitionContext: UIViewControllerContextTransitioning!) -> NSTimeInterval { 
    return 2 
} 

func animateTransition(transitionContext: UIViewControllerContextTransitioning!) { 
    let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey) as UIViewController 
    let toViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey) as UIViewController 

    toViewController.view.transform = CGAffineTransformMakeScale(0.5, 0.5) 
    toViewController.view.alpha = 0 

    transitionContext.containerView().addSubview(fromViewController.view) 
    transitionContext.containerView().addSubview(toViewController.view) 
    transitionContext.containerView().bringSubviewToFront(toViewController.view) 

    UIView.animateWithDuration(self.transitionDuration(transitionContext), animations: { 
     fromViewController.view.transform = CGAffineTransformScale(fromViewController.view.transform, 2, 2) 
     fromViewController.view.alpha = 1 

     toViewController.view.transform = CGAffineTransformMakeScale(1, 1) 
     toViewController.view.alpha = 1 
    }, completion: { finished in 
     transitionContext.completeTransition(!transitionContext.transitionWasCancelled()) 
    }) 
} 

}

和代码来呈现：

let targetViewController = self.storyboard.instantiateViewControllerWithIdentifier("Level1ViewController") as Level1ViewController 
    let td = FadeAndGrowAnimationController() 

    targetViewController.transitioningDelegate = td 
    targetViewController.modalPresentationStyle = .Custom 

    self.presentViewController(targetViewController, animated: true, completion: nil) 

正如你所看到的，一个相当基本的动画。我在这里错过了什么吗？就像我说的，它表现得很好，然后解散了99.99％的完美，但解雇后的视图控制器被莫名其妙地删除。在这种情况发生后，iPad会显示一个黑屏 - 完全黑屏。

Answer 1

这似乎是一个iOS8的错误。我找到了解决方案，但它是贫民窟。当一个视图应该是在屏幕上，但不是转场之后，它需要被重新添加到窗口是这样的：

BOOL canceled = [transitionContext transitionWasCancelled]; 
[transitionContext completeTransition:!canceled]; 
if (!canceled) 
    { 
    [[UIApplication sharedApplication].keyWindow addSubview: toViewController.view]; 
    } 

您可能需要摆弄它查看您添加回窗口，是否以取消或取消的方式执行此操作，并且可能确保仅在解雇和不提交时执行此操作。

来源：Container view disappearing on completeTransition: http://joystate.wordpress.com/2014/09/02/ios8-and-custom-uiviewcontrollers-transitions/

Answer 2

了您正在使用的Xcode 6同样的问题IOS 8.1

我的SWIFT代码completeTransition

if let window = UIApplication.sharedApplication().keyWindow { 
    if let viewController = window.rootViewController { 
     window.addSubview(viewController.view) 
    } 
}