自定义的Present Modal在IOS7.x下不会自动更新系统状态栏

自定义 Present/Dismiss 动画部分请参考上一篇：定制Segue
- OverlaySegue
在ios8/9上，OverlaySegue弹出目标视图控制器后，系统状态栏自动更新为新的样式，presented view controller如下配置

- (UIStatusBarStyle)preferredStatusBarStyle
{
return UIStatusBarStyleLightContent;
}

使用Ios7真机测试后，发现状态栏还是保持着源视图控制器(presenting view controller)的样式，几经折腾后找到解决方案

- (void)perform
{
self.destinationViewController.transitioningDelegate = self.transitioningDelegate;
self.destinationViewController.modalPresentationStyle = UIModalPresentationCustom;
self.destinationViewController.modalPresentationCapturesStatusBarAppearance = YES;

[self.sourceViewController presentViewController:self.destinationViewController animated:YES completion:NULL];
}

IOS7机型上这一行代码即可解决问题，从调用栈的相似度来看，修改后基本保持了同样的行为

modalPresentationCapturesStatusBarAppearance = YES

IOS9调用栈

-[ChildViewController preferredStatusBarStyle]
-[UIApplication _updateCurrentStatusBarViewControllerAppearance] ()
-[UIViewController setNeedsStatusBarAppearanceUpdate] ()
-[UIViewController _setPresentedStatusBarViewController:] ()
-[_UIViewControllerTransitionCoordinator _applyBlocks:releaseBlocks:] ()
-[_UIViewControllerTransitionContext __runAlongsideAnimations] ()
-[UIViewAnimationState _runAlongsideAnimations] ()
-[UIViewAnimationState pop] ()
+[UIViewAnimationState popAnimationState] ()
+[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] ()
[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion:] ()
[TVOverlayAnimatedTransitioning animateTransition:]

IOS7调用栈

-[ChildViewController preferredStatusBarStyle]
-[UIApplication _updateCurrentStatusBarViewControllerAppearance] ()
-[_UIViewControllerTransitionCoordinator _applyBlocks:releaseBlocks:] ()
-[_UIViewControllerTransitionContext __runAlongsideAnimations] ()
-[UIViewAnimationState _runAlongsideAnimations] ()
-[UIViewAnimationState pop] ()
+[UIViewAnimationState popAnimationState] ()
+[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] ()
+[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion:] ()
-[TVOverlayAnimatedTransitioning animateTransition:]

API文档对modalPresentationCapturesStatusBarAppearance的说明中，默认值就是NO，暂时没弄清楚为什么新系统版本下，明明说了状态栏样式不由弹出视图控制器决定，但却那么做了。

系统默认的present modal弹出方式是没有这个问题的，我的OverlaySegue有点特殊，源视图控制器和目标视图控制器同时存在，目标视图覆盖在源视图上面，也就是说源视图没有从window中移除，有时间再细究。