title: Make UISearchController search bar automatically active
body: <p>I've implemented a UISearchController with its search bar in a navigatiom bar and I would like to make the search bar active when the view is loaded. When I say active, I mean that the keyboard appears and the user can type his/her search without tap the search bar.</p>
  
  <p>I initialised the UISearchController with the following code:</p>
  
  <pre><code>- (void)viewDidLoad
  {
      self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
      [self.searchController setSearchResultsUpdater:self];
      [self.searchController setDimsBackgroundDuringPresentation:NO];
      [self.searchController setHidesNavigationBarDuringPresentation:NO];
      [self.navigationItem setTitleView:self.searchController.searchBar];
  
      [self setDefinesPresentationContext:YES];
  
      [self.searchController.searchBar setDelegate:self];
      [self.searchController.searchBar setShowsCancelButton:YES];
      [self.searchController.searchBar setPlaceholder:@"City or Airfield"];
  
      [self.searchController.searchBar sizeToFit];
  }
  </code></pre>
  
  <p>I've tried to make my search controller active, call <code>[self.searchController.searchBar becomeFirstResponder]</code> and directly call <code>searchBarSearchButtonClicked</code> but nothing works.</p>