iOS 13如何在navigationBar中隐藏UISearchController searchBar

import UIKit

class ViewController: UIViewController, UISearchControllerDelegate {
    var searchController: UISearchController!

    override func viewDidLoad() {
        super.viewDidLoad()
        
        searchController = UISearchController(searchResultsController: nil)
        searchController.searchBar.placeholder = "Search"
        searchController.searchBar.delegate = self
        
        // 隐藏搜索栏
        searchController.searchBar.isHidden = true
        
        // 在搜索时隐藏导航栏
        searchController.hidesNavigationBarDuringPresentation = true
        
        // 在搜索时不模糊背景
        searchController.obscuresBackgroundDuringPresentation = false
        
        navigationItem.searchController = searchController
        navigationItem.hidesSearchBarWhenScrolling = false
    }
}

extension ViewController: UISearchBarDelegate {
    func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
        // 显示搜索栏
        searchController.searchBar.isHidden = false
    }
}