title: UISearchController wrong animation on swipe back then disappearing
body: <p>To make this short, I have a main view controller that has the navigation bar hidden, from that VC's navigation controller, I push another view controller which has the navigation bar visible. Then I add a searchController to the navigationItem to add the searchBar when I scroll down. Everything is working fine until you swipe back to pop the VC.</p>
  
  <p>The navigation bar will animate leave the screen with the VC, but the searchBar will animate as if it's going up in place. What's worse is if I cancel the swipe to pop, the whole searchBar disappears and a black view appears instead (I think the searchController background ow whatever view background).</p>
  
  <p>I tried everything, it's a few lines of code yet I've been pulling my hair to solve this. I know I can just disable swipe to pop but I don't want that(+ even when pressing back the searchBar animates in the same weird way) and I don't want to add a searchBar in any other way.</p>
  
  <p>In the attached video I'm just swiping with my finger to show the animation.</p>
  
  <p><a href="https://i.stack.imgur.com/h4u2c.gif" rel="noreferrer"><img src="https://i.stack.imgur.com/h4u2c.gif" alt="desc"></a></p>
  
  <pre><code>- (void)viewDidLoad {
      [super viewDidLoad];
      self.definesPresentationContext = YES;
      [self.navigationController setNavigationBarHidden:NO];
  
      if (@available(iOS 11.0, *)) {
          self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
          _searchController.delegate = self;
          _searchController.searchResultsUpdater = self;
          _searchController.searchBar.placeholder = @"Search";
          self.navigationItem.searchController = _searchController;
          self.navigationItem.hidesSearchBarWhenScrolling = YES;
      }
  }
  </code></pre>