我正在尝试进行一个非常简单的过渡：一个视图将屏幕的一半移动到左侧,而第二个(“到”)视图移动半个屏幕.
我有动画工作,但当我反转动画时,我看到一个闪烁. “to”视图(即原始视图)在0,0的原点可见,尽管我设置了不同的帧.
我转储了视图层次结构.帧设置正确(-100 0; 320 480用于查看),但是它显示为0,0.视图的屏幕截图是否缓存在动画的某处？
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *container = [transitionContext containerView];
CGRect offsetCoverRect = CGRectMake(-100.0,0.0,320,480);
CGRect detailsRect = CGRectMake(-100.0 + 320.0,480);
CGRect detailsOutsideRect = CGRectMake(320.0,480);
CGRect normalRect = CGRectMake(0.0,480);
if (self.revealDetails)
{
toViewController.view.frame = detailsOutsideRect;
[container addSubview:toViewController.view];
}
else
{
[container insertSubview:toViewController.view belowSubview:fromViewController.view];
// reversing… set the frame to the original offset (shows at 0,0 for a moment)
toViewController.view.frame = offsetCoverRect;
}
[UIView animateKeyframesWithDuration:2 delay:0 options:0 animations:^{
if (self.revealDetails)
{
fromViewController.view.frame = offsetCoverRect;
toViewController.view.frame = detailsRect;
}
else
{
fromViewController.view.frame = detailsOutsideRect;
toViewController.view.frame = normalRect;
}
} completion:^(BOOL finished) { [transitionContext completeTransition:finished]; }];
}
更新：
它似乎与UIModalPresentationCustom有关.我需要使用它,以便在转换完成时不删除from视图.但是,它似乎假设反向转换的from视图控制器从0,0开始.
更新2：
使用以下代码非常容易重现：
UIView *snapshot = [containerView snapshotViewAfterScreenUpdates:NO]; [containerView addSubview:snapshot];
以上将显示以屏幕为中心的视图,无论我在动画之前设置的实际帧或中心.
