ios7 hiden status bar

First of all,Excel the method "prefersStatusBarHidden" in view controllers to set the status bar hiden 'YES' when inited

[self perfersStatusBarHiden]

Second,Excel the method "performSelector:@selector(setNeedsStatusBarAppearanceUpdate)" to set the view controller based status bar apperance 'NO'

[self performSelector:@selector(setNeedsStatusBarAppearanceUpdate)]

Then ,actualize the seletor method

-(BOOL) setNeedsStatusBarAppearanceUpdate
{
          return YES;
}