ios - UIViewController 动画转换在 iOS8 中失败

Question

我有一个自定义的 UIViewController 转换——在 iOS7 中，它工作得非常好。

但是，在 iOS 8 上运行时，我遇到了问题。具体来说，当呈现的 View Controller 被关闭时，原始 View Controller 的 View 完全消失——给我留下一个完全空白的屏幕。这是我的代码:

@implementation DDCardTransition

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext {
    return 0.5f;
}

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

    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

    CGRect endFrame = self.destinationFrame;

    if (self.presenting) {
        fromViewController.view.userInteractionEnabled = NO;
        toViewController.view.layer.cornerRadius = 6.0f;

        UIView *tintAdjustmentView = [UIView new];
        tintAdjustmentView.frame = fromViewController.view.frame;
        tintAdjustmentView.backgroundColor = [UIColor blackColor];
        tintAdjustmentView.alpha = 0.f;

        [transitionContext.containerView addSubview:fromViewController.view];
        [transitionContext.containerView addSubview:tintAdjustmentView];
        [transitionContext.containerView addSubview:toViewController.view];

        CGRect startFrame = endFrame;
        startFrame.origin.y += [UIScreen mainScreen].bounds.size.height;
        toViewController.view.frame = startFrame;

        [CATransaction begin];
        [CATransaction setCompletionBlock:^{
            [transitionContext completeTransition:YES];
        }];

        CABasicAnimation *frameAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
        frameAnimation.timingFunction = [CAMediaTimingFunction functionWithControlPoints:0.1f :0.8f :0.0 :1.0];
        frameAnimation.duration = [self transitionDuration:transitionContext];
        frameAnimation.fromValue = [NSValue valueWithCGPoint:CGPointMake(CGRectGetMidX(startFrame), CGRectGetMidY(startFrame))];
        frameAnimation.toValue = [NSValue valueWithCGPoint:CGPointMake(CGRectGetMidX(endFrame), CGRectGetMidY(endFrame))];
        toViewController.view.layer.position = [frameAnimation.toValue CGPointValue];
        [toViewController.view.layer addAnimation:frameAnimation forKey:@"position"];

        CABasicAnimation *opacityAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
        opacityAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
        opacityAnimation.duration = 0.3f;
        opacityAnimation.fromValue = @(0.f);
        opacityAnimation.toValue = @(0.5f);
        tintAdjustmentView.layer.opacity = [opacityAnimation.toValue floatValue];
        [tintAdjustmentView.layer addAnimation:opacityAnimation forKey:@"opacity"];

        [CATransaction commit];
    }
    else {
        toViewController.view.userInteractionEnabled = YES;

        UIView *tintAdjustmentView = [UIView new];
        tintAdjustmentView.frame = toViewController.view.frame;
        tintAdjustmentView.backgroundColor = [UIColor blackColor];
        tintAdjustmentView.alpha = 0.5f;

        [transitionContext.containerView addSubview:toViewController.view];
        [transitionContext.containerView addSubview:tintAdjustmentView];
        [transitionContext.containerView addSubview:fromViewController.view];

        endFrame.origin.y += [UIScreen mainScreen].bounds.size.height;

        [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
            fromViewController.view.frame = endFrame;
            tintAdjustmentView.alpha = 0.f;
        } completion:^(BOOL finished) {
            [transitionContext completeTransition:YES];
        }];
    }
}

@end

知道为什么这在 iOS8 中不再有效吗？

谢谢!

Answer 1

以下代码在 xcode GM 中运行良好:

func animateTransition(transitionContext: UIViewControllerContextTransitioning!)  {

    let fromViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
    let fromViewControllerView = transitionContext.viewForKey(UITransitionContextFromViewKey)
    let containerView = transitionContext.containerView()

    fromViewControllerView?.frame = transitionContext.finalFrameForViewController(fromViewController!)
    fromViewControllerView?.frame.origin.y = containerView.bounds.height

    containerView.addSubview(fromViewControllerView!)

    UIView.animateWithDuration(transitionDuration(transitionContext),
        delay: 0.0,
        options: .AllowUserInteraction,
        animations: {
            fromViewControllerView!.center.y = containerView.bounds.size.height/2
        },
        completion: { (completed: Bool) -> Void in
            transitionContext.completeTransition(completed)
        }
    )