Xcode-除非这是根视图控制器，否则视图控制器的搜索栏不可见

Question

具有搜索功能的普通视图控制器：

class PlacesViewController: UIViewController {
     @IBOutlet weak var tableView: UITableView!
     let searchController = UISearchController(searchResultsController: nil)
     override func viewDidLoad() {
          super.viewDidLoad()
          searchController.searchResultsUpdater = self
          searchController.obscuresBackgroundDuringPresentation = false
          searchController.searchBar.placeholder = "Search Permits"
          navigationItem.searchController = searchController
          definesPresentationContext = true
      }
  }

当它是根视图控制器时，搜索栏将显示为OK。但是，如果我按如下所示通过按钮到达，则搜索栏不可见：:

   @IBAction func placesPressed(_ sender: Any) {
     let placesVC = storyboard?.instantiateViewController(withIdentifier:”PlacesViewController”) as? PlacesViewController
     if let placesVC = placesVC {
       placesVC.modalPresentationStyle = .currentContext // tried variations
       present(placesVC, animated: false, completion: nil)
     }
   }