IOS Hide Nav Bar

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    MyCustomNavController* navController = (MyCustomNavController*)self.parentViewController;
    if( [scrollView.panGestureRecognizer translationInView:self.view].y  < 0.0f ) {
        [navController setExpanded:YES animated:YES];
    } else if ([scrollView.panGestureRecognizer translationInView:self.view].y  > 0.0f  ) {
        [navController setExpanded:NO animated:YES];
    }

}