gistfile1.txt

__block BOOL flag = YES; //0 up 1 down
    
    UINavigationBar *navbar = [[self navigationController] navigationBar];
    
    [UIView animateWithDuration:0.3 animations:^(void)
     {
         if ([[UIApplication sharedApplication] respondsToSelector:@selector(setStatusBarHidden:withAnimation:)]) {
             [[UIApplication sharedApplication] setStatusBarHidden:flag withAnimation:NO];
         } 
         if (flag) {
             navbar.frame = CGRectMake(0, -44, 320, 44); 
         }
         else {
             navbar.frame = CGRectMake(0, 20, 320, 44);
         }
        
     }];