隐藏状态栏

-(void)viewWillDisappear:(BOOL)animated

{
    [ super viewWillDisappear :animated];
    [[ UIApplication sharedApplication ] setStatusBarHidden : NO ];

}
-( void )viewWillAppear:( BOOL )animated
{
    [ super viewWillAppear :animated];
    [[ UIApplication sharedApplication ] setStatusBarHidden : YES ];
}