我在导航控制器中嵌入了一个控制器。假设我有一个按钮，可以稍微重新定位self.navigationController.navigationBar。然后，我使用任何控制器执行presentViewControllerAnimated（无论是否导航），并将其关闭后，导航栏返回其原始位置（实际上，在关闭动画开始时它处于其原始位置）。在iOS 6及更低版本中，该栏不会自动重新定位。知道如何防止在iOS 7中重新定位吗？
最佳答案
好的，所以我终于正确了。
首先-Apple不希望我们更改UINavigationBar的位置。因此，您应该不惜一切代价避免它。以我为例，我有一个应用程序要修复，该应用程序移动了UINavigationBar以显示滑出菜单。滑出菜单问题的正确解决方案是将UINavigationController放进内部-然后您可以将整个UINavigationController连同其内容（无论它是什么）一起滑动，一切正常。由于某种原因，UINavigationController不在此应用程序中。因此，我不得不求助于黑客。如果可以选择不使用此方法，请不要使用此方法。这是一个hack，可能会在进一步的iOS版本中中断，Apple肯定不会喜欢它。
首先，探索iOS7中的新过渡系统：http://www.doubleencore.com/2013/09/ios-7-custom-transitions/
然后，替换：
[self presentViewController:navigationController animated:YES completion:nil];
与
if([UIApplication iOS7]) /* or any other custom iOS7 detection method you implement */
{ /* we simulate old transition with nav bar slided out */
navigationController.transitioningDelegate = [OMModalTransitionDelegate new];
}
[self presentViewController:navigationController animated:YES completion:nil];
因此，我们需要一个过渡委托来模拟标准行为并完成技巧。
#import "OMModalTransitionDelegate.h"
#import "OMAnimatedTransitioning.h"
@implementation OMModalTransitionDelegate
- (id <UIViewControllerAnimatedTransitioning>)animationControllerForPresentedController:(UIViewController *)presented presentingController:(UIViewController *)presenting sourceController:(UIViewController *)source
{
OMAnimatedTransitioning *transitioning = [OMAnimatedTransitioning new];
return transitioning;
}
- (id <UIViewControllerAnimatedTransitioning>)animationControllerForDismissedController:(UIViewController *)dismissed
{
OMAnimatedTransitioning *transitioning = [OMAnimatedTransitioning new];
transitioning.reverse = YES;
return transitioning;
}
@end
现在是实际的动画管理器（您必须自己在UINavigationBar的类别中实现sharedBar）：
static NSTimeInterval const DEAnimatedTransitionDuration = 0.4f;
static NSTimeInterval const DEAnimatedTransitionMarcoDuration = 0.15f;
@implementation OMAnimatedTransitioning
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *container = [transitionContext containerView];
UIView *superView = [UINavigationBar sharedBar].superview;
CGRect barFrame = [UINavigationBar sharedBar].frame;
if(self.reverse)
{ /* Trick - first, remove the bar from it's superview before animation starts */
[[UINavigationBar sharedBar] removeFromSuperview];
}
CGRect oldFrame = container.bounds;
if (self.reverse)
{
[container insertSubview:toViewController.view belowSubview:fromViewController.view];
}
else
{
toViewController.view.frame = oldFrame;
toViewController.view.transform = CGAffineTransformMakeTranslation(0, CGRectGetHeight(oldFrame));
[container addSubview:toViewController.view];
}
[UIView animateKeyframesWithDuration:DEAnimatedTransitionDuration delay:0 options:0 animations:^
{
if (self.reverse)
{
fromViewController.view.transform = CGAffineTransformMakeTranslation(0, CGRectGetHeight(oldFrame));
double delayInSeconds = 0.01; /* Trick - after an imperceivable delay - add it back - now it is immune to whatever Apple put there to move it */
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void)
{
[UINavigationBar sharedBar].frame = barFrame;
[superView addSubview:[UINavigationBar sharedBar]];
});
}
else
{
toViewController.view.transform = CGAffineTransformIdentity;
}
} completion:^(BOOL finished) {
[transitionContext completeTransition:finished];
}];
}
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
return DEAnimatedTransitionDuration;
}
@end