message: Set hidden in willAppear but kept false if search open
  Simplified code by always setting hidden in viewWillAppear. But if the search is open then ignore the prop and keep the navigation bar hidden. Will set it to the prop value in viewWillLayoutSubviews
diff: NSInteger crumb = [self.navigationController.viewControllers indexOfObject:self];
  UIViewController *previousController = crumb > 0 ? [self.navigationController.viewControllers objectAtIndex:crumb - 1] : nil;
  NVNavigationBarView *navigationBar = (NVNavigationBarView *) [self.view viewWithTag:NAVIGATION_BAR];
  - BOOL setHidden = YES;
  + BOOL hidden = navigationBar.hidden;
  if (@available(iOS 11.0, *)) {
  - setHidden = !previousController.navigationItem.searchController.active;
  - }
  - if (setHidden) {
  - [self.navigationController setNavigationBarHidden:navigationBar.hidden];
  + hidden = hidden || previousController.navigationItem.searchController.active;
  }
  + [self.navigationController setNavigationBarHidden:hidden];
  if (navigationBar.title.length != 0) {
  [self.navigationItem setTitle:navigationBar.title];
  }
  