ios - 如何进行自定义 View Controller 转换，其中一部分是 UIView animateWithDuration 而另一部分是 transitionFromView？

Question

我似乎无法弄清楚如何同时执行 animateWithDuration和 transitionWithView在 iOS 7 中使用自定义 View Controller 转换。

这是我转换 View 的代码。我基本上想从初始 View (表示为屏幕截图)过渡到使其模糊和变暗(我将初始屏幕截图图像溶解为模糊图像并在其上添加一个深色透明 View ):

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
    ImageGalleryPageViewController* toViewController = (ImageGalleryPageViewController *)[transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIViewController* fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];

    // Add an image view representing the view controller we're transitioning from
    UIImage *fromVCImage = [self convertViewToImage:fromViewController.view];
    UIImageView *fromVCImageView = [[UIImageView alloc] initWithImage:fromVCImage];

    [[transitionContext containerView] addSubview:fromVCImageView];

    // Create a blurred version of the same image view
    GPUImageiOSBlurFilter *blurFilter = [[GPUImageiOSBlurFilter alloc] init];
    blurFilter.blurRadiusInPixels = 2.0;

    UIImage *blurredFromVCImage = [blurFilter imageByFilteringImage:fromVCImage];
    UIImageView *blurredFromVCImageView = [[UIImageView alloc] initWithImage:blurredFromVCImage];

    // Add a dark overlay
    UIView *darkOverlay = [[UIView alloc] initWithFrame:fromVCImageView.frame];
    darkOverlay.backgroundColor = [UIColor blackColor];
    darkOverlay.alpha = 0.0;

    [[transitionContext containerView] addSubview:darkOverlay];

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        darkOverlay.alpha = 0.8;
    } completion:^(BOOL finished) {
    }];

    [UIView transitionFromView:fromVCImageView toView:blurredFromVCImageView duration:[self transitionDuration:transitionContext] options:UIViewAnimationOptionTransitionCrossDissolve completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}

但只有模糊部分有效，变暗无效。如果我删除最后一个 block 并只保留第一个 block ，那么变暗效果很好。我似乎不能两者兼得。

我怎样才能让它们都工作？我知道可能有一种解决方法可以调整模糊图像的 alpha，但我想使用 transitionFromView:以获得更高级的效果。

Answer 1

在 transitionWithView:... , 逻辑或 UIViewAnimationOptionBeginFromCurrentState作为您的选择之一。否则，由于另一个动画刚刚开始，深色叠加动画会突然结束。包含此选项会告诉下一个动画从上一个动画的当前状态开始。