Show/hide navigation bar on push/pop

ViewController.m

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    [self.navigationController setNavigationBarHidden:NO animated:YES];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    if (self.isMovingFromParentViewController)
        [self.navigationController setNavigationBarHidden:YES animated:YES];
}