无法在 UISearchController 上获得 becomeFirstResponder 工作

Question

在viewDidLoad():

searchController = UISearchController(searchResultsController: nil)
let cancelButtonAttributes = [NSAttributedStringKey.foregroundColor: UIColor.white]
UIBarButtonItem.appearance(whenContainedInInstancesOf: [UISearchBar.self]).setTitleTextAttributes(cancelButtonAttributes, for: .normal)

searchController?.dimsBackgroundDuringPresentation = false
searchController?.searchResultsUpdater = self
searchController?.delegate = self
searchController?.searchBar.tintColor = UIColor.black
searchController?.searchBar.barTintColor = UIColor(white: 0.9, alpha: 0.9)
searchController?.searchBar.placeholder = NSLocalizedString("Search", comment: "")
searchController?.hidesNavigationBarDuringPresentation = false
self.navigationItem.titleView = self.searchController?.searchBar

searchController?.isActive = true
self.searchController?.becomeFirstResponder()
self.searchController?.searchBar.becomeFirstResponder()

这是委托方法：

extension SearchMembers :  UISearchControllerDelegate {
    func didPresentSearchController(searchController: UISearchController){
          self.searchController?.searchBar.becomeFirstResponder()
    }
}

在我的测试中，didPresentSearchController(searchController:) 从未被调用过。

我不知道为什么，但无论我做什么都是行不通的。

有什么想法吗？

编辑 唯一有效的解决方案

      delay(0.6) {
         self.searchController?.searchBar.becomeFirstResponder()
        }

这会造成不必要的延迟

Answer 1

根据didPresentSearchController的documentation：

该方法仅在搜索控制器自动呈现时调用。如果您明确显示搜索控制器，则不会调用它。

如果您想显式显示搜索结果界面，请将搜索控制器包装在 UISearchContainerViewController 对象中并改为显示该对象。