info.plist文件中，View controller-based status bar appearance项设为YES，则View controller对status bar的设置优先级高于application的设置。为NO则以application的设置为准，view controller的PRefersstatusBarHidden方法无效，是根本不会被调用的。

1．View controller-based status bar appearance设为YES。

这时 view controller中对status bar的设置优先级高于application的设置，用下面的方式隐藏status bar。

1.1 在view controller中调用setNeedsStatusBarAppearanceUpdate，更新status bar的显示

 1 - (void)viewDidAppear:(BOOL)animated
 2 {
 3     [super viewDidAppear:animated];
 4 
 5     if ([self respondsToSelector:@selector(setNeedsStatusBarAppearanceUpdate)]) {
 6         [self prefersStatusBarHidden];
 7         [self performSelector:@selector(setNeedsStatusBarAppearanceUpdate)];
 8     }
 9 }    

1.2 覆盖view controller的prefersStatusBarHidden的实现，返会YES。

1 - (BOOL)prefersStatusBarHidden
2 {
3     return YES;
4 }

2．View controller-based status bar appearance设为NO

这时application的设置优先级最高，用下面的方式隐藏status bar:

1 [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:NO];

3．结论

• 如果View controller-based status bar appearance 设为NO，iOS6和iOS7都是用下面的方法隐藏status bar。

1 [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:NO];

• 如果View controller-based status bar appearance 设为YES，则需要判断当前是iOS6还是iOS7。

　　如果是iOS6，则还通过sharedApplication隐藏。

　　如果是iOS7，则用setNeedsStatusBarAppearanceUpdate加prefersStatusBarHidden的方式来隐藏 status bar。

4．取info.plist中 View controller-based status bar appearance中的设置

 1 NSNumber *isVCBasedStatusBarAppearanceNum = [[NSBundle mainBundle]objectForInfoDictionaryKey:@"UIViewControllerBasedStatusBarAppearance"];
 2 if (isVCBasedStatusBarAppearanceNum) {
 3     _isVCBasedStatusBarAppearance = isVCBasedStatusBarAppearanceNum.boolValue;
 4 } else {
 5     _isVCBasedStatusBarAppearance = YES; // default
 6 }