我在UINavigationController中嵌入的视图控制器之间有一个自定义推送转换,当使用iOS 7/8构建时它工作正常但在针对iOS 9 SDK构建时呈现错误的布局.
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
[transitionContext.containerView addSubview:toViewController.view];
...
然后它继续并执行动画.问题是toViewController的内容,即使它使用正确的顶部布局指南自动布局约束,也会显示导航栏后面的内容.
尽管如此,它在iOS 8上工作正常,如果我们强制重绘(例如,将应用程序发送到后台并将其恢复,在顶部呈现模式并将其解除等)将导致整个自动布局系统重绘并且toViewController的视图跳转到正确的位置(作为顶部布局指南,导航栏中的x像素,而不是设备屏幕顶部的x像素).
[self.view setNeedsUpdateConstraints]; [self.view layoutIfNeeded];
放入viewDidAppear：动画,但不适用于viewDidLoad或viewWillAppear：动画.这不是一个解决方案,因为当在viewDidAppear：animated上发生重绘时,用户会看到视图跳跃
解决方法
我已经设法通过在addSubview :: add之前添加以下行来解决我的问题
toViewController.view.frame = [transitionContext finalFrameForViewController:toViewController];
来自Apple的finalFrameForViewController:文档
Returns the ending frame rectangle for the specified view controller’s
view.The rectangle returned by this method represents the size of the corresponding view at the end of the transition. For the view being covered during the presentation,the value returned by this method might be CGRectZero but it might also be a valid frame rectangle.
