推送下一个视图控制器时，UISearchBar的延迟被删除

Question

Xcode 10.1，Swift 4.2

ViewController A具有LargeTitles，UISearchController和UITableView。

在选择TableViewCell之后推送ViewController B（也是一个TableView）时，UISearchBar占用的空间会有一个延迟，如动画中所示。

ViewController B也有一个UISearchController，但是按照通常的行为，它会被隐藏，直到用户在屏幕上向下拖动。

有谁知道如何防止这种情况发生？

附加信息和代码：

ViewController A当点击单元格时，它会在Storyboard上使用Show（例如Push）segue选择Animates来推动ViewController B.使用prepareForSegue方法注入数据。

performSegue(withIdentifier: "showLogbook", sender: self)

ViewController B：

class LogbookVC: UIViewController, UITableViewDelegate, UITableViewDataSource, UISearchBarDelegate, UISearchResultsUpdating {

    //Extract
    private let searchController = UISearchController(searchResultsController: nil)


    @IBOutlet private var addButton: UIBarButtonItem!
    @IBOutlet private var shareButton: UIBarButtonItem!
    @IBOutlet private var backButton: UIBarButtonItem!
    @IBOutlet private var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.delegate = self
        tableView.dataSource = self
        tableView.rowHeight = 75.0
        //loading tableView data
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    self.navigationController?.navigationBar.prefersLargeTitles = true
    self.definesPresentationContext = true
    configureSearchController()
    fetchAndSortLogEntries()
}

private func configureSearchController() {
    navigationItem.searchController = searchController
    searchController.searchResultsUpdater = self
    searchController.searchBar.scopeButtonTitles = ["Newest", "Oldest"]
    searchController.searchBar.delegate = self
    searchController.searchBar.barStyle = .black
    searchController.searchBar.tintColor = K.Colors.appMid
    searchController.searchBar.keyboardAppearance = .dark
    searchController.searchBar.returnKeyType = .done
    searchController.dimsBackgroundDuringPresentation = false
    let attributes = [NSAttributedString.Key.foregroundColor: K.Colors.appMid]
    UIBarButtonItem.appearance(whenContainedInInstancesOf: [UISearchBar.self]).setTitleTextAttributes(attributes, for: .normal)
    searchController.searchBar.setValue("Reset", forKey: "_cancelButtonText")
    let searchBarCancelButton = searchController.searchBar.value(forKey: "cancelButton") as? UIButton
    searchBarCancelButton?.setTitle("Reset", for: .normal)
}

Answer 1

我认为这是一个错误，当使用LargeTitles并在相邻的UISearchControllers有两个ViewControllers。

我发现通过在UISearchController中将NavigationItem添加到viewDidAppear修复了问题，但是必须异步添加它，否则会发生以下致命错误：

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Only one palette with a top boundary edge can be active outside of a transition.

需要将此代码添加到ViewControllers，以便在导航回ViewController A时也可以防止问题行为。

Xcode 10.1，Swift 4.2

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        DispatchQueue.main.async {
            self.navigationItem.searchController = self.searchController
            self.searchController.searchResultsUpdater = self
            self.searchController.searchBar.delegate = self
        }
    }

此代码将确保在下一个NavigationBar出现时不隐藏ViewController：

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        navigationController?.isNavigationBarHidden = false
    }