解决iOS 7中短时间动画案例

这个是解决iOS 7中短时间动画案例，源码SafeTransition，解决iOS 7中短时间内连续push或者pop view动画操作而产生崩溃的bug。 bug描述原因为 Can not add self as subview。可以用下面这段代码重现这个bug： - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; UIViewController *vc = [[UIViewController alloc] init]; [self.navigationController pushViewController:vc animated:YES]; } 将会得到以下错误: 2014-07-03 11:54:25.051 Demo[2840:60b] nested push animation can result in corrupted navigation bar 2014-07-03 11:54:25.406 Demo[2840:60b] Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.