iOS7下隐藏statusbar的详细研究

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)animated2{3[super viewDidAppear:animated];45if([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)prefersStatusBarHidden2{3returnYES;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1NSNumber *isVCBasedStatusBarAppearanceNum = [[NSBundle mainBundle]objectForInfoDictionaryKey:@"UIViewControllerBasedStatusBarAppearance"];2if(isVCBasedStatusBarAppearanceNum) {3_isVCBasedStatusBarAppearance =isVCBasedStatusBarAppearanceNum.boolValue;4}else{5_isVCBasedStatusBarAppearance = YES;//default6}