iOS6和iOS7在隐藏 Status Bar 三种方式比较:

Storyboard

界面上选中UIViewController,最右边Simulated Metrics找到 Status Bar 设定成 None

ViewController

iOS 6 
通过[UIApplication sharedApplication] 取得app的单例，然后调用setStatusBarHidden方法隐藏 Status Bar。

UIApplication *app = [UIApplication sharedApplication];
[app setStatusBarHidden:YES withAnimation:YES];

iOS 7 

- (BOOL)prefersStatusBarHidden
{
    return YES;
}
//特殊情况时,调用下面方法,强制重新绘製 Status Bar
[self setNeedsStatusBarAppearanceUpdate];

Info.plist

不但要在 Info.plist 中增加 Status bar is initially hidden一行,选择值为 YES,

还需增加 View controller-based status bar appearance 一行,选择值为 NO。