导航栏消失 Change Root ViewController 然后重新赋值

Question

当我的应用程序向 firebase 发出请求时，我已将启动屏幕设置为根视图，然后在请求完成后重新分配根视图。不幸的是，当我这样做时，我的导航栏消失或被新的根视图覆盖。当我运行模拟器时，我可以短暂地看到导航栏，然后它被我的 TableViewController 覆盖。我该如何防止这种情况发生？

这是我在 AppDelegate 中实现这一切的代码：

    var window: UIWindow?
let searchManager = SearchManager()

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    makeRootViewLaunchScreen()
    FirebaseApp.configure()
    searchManager.getMosaicTitles { results in
        self.searchManager.listOfMosaics = results
        self.stopDisplayingLaunchScreen()
    }
    // Adds border to bottom of the nav bar
    UINavigationBar.appearance().shadowImage = UIImage.imageWithColor(color: UIColor(red:0.00, green:0.87, blue:0.39, alpha:1.0))
    // Override point for customization after application launch.
    return true
}

func makeRootViewLaunchScreen() {
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "LaunchScreen", bundle: nil)
    let viewController = mainStoryboard.instantiateViewController(withIdentifier: "launchScreen")
    UIApplication.shared.keyWindow?.rootViewController = viewController
}

func stopDisplayingLaunchScreen() {
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let viewController = mainStoryboard.instantiateViewController(withIdentifier: "centralViewController") as? SearchResultsTableViewController
    viewController?.searchManager = searchManager
    UIApplication.shared.keyWindow?.rootViewController = viewController
    UIApplication.shared.keyWindow?.rootViewController?.navigationController?.isNavigationBarHidden = false
}

如您所见，我尝试使用 UIApplication.shared.keyWindow?.rootViewController?.navigationController?.isNavigationBarHidden = false 强制显示导航栏，但没有显示。我的应用仍然是这样的：

Answer 1

您正在将 UIViewController 设置为根控制器。你想要做的是设置一个 UINavigationController 作为你的 Root 控制器。

要么在你的故事板中创建一个新的导航控制器并加载它而不是加载 "centralViewController"，要么像这样修改你的函数：

func stopDisplayingLaunchScreen() {
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

    if let viewController = mainStoryboard.instantiateViewController(withIdentifier: "centralViewController") as? SearchResultsTableViewController {

        viewController.searchManager = searchManager

        // create a new UINavigationController
        let newNavVC = UINavigationController()

        // set the "root" VC of the NavVC to your SearchResultsTableViewController
        newNavVC.setViewControllers([viewController], animated: false)

        // use the new NavVC as the new rootViewController
        UIApplication.shared.keyWindow?.rootViewController = newNavVC
        UIApplication.shared.keyWindow?.rootViewController?.navigationController?.isNavigationBarHidden = false

    }
}

注意：未经测试，但这应该可以帮助您。

编辑：另一种方法...

不要交换密钥 window 的根控制器，而是创建一个 ViewController 来指示您正在初始化/检索数据。 VC 可以是导航控制器的 "root"。

将你的 searchManager.getMosaicTitles 函数放在 that VC 中。完成后，将导航控制器中的当前 "launch" 控制器替换为 表VC。它看起来像这样：

// note: searchManager will have to be a reference back to AppDelegate.searchManager
searchManager.getMosaicTitles { results in
    self.searchManager.listOfMosaics = results

    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

    if let viewController = mainStoryboard.instantiateViewController(withIdentifier: "centralViewController") as? SearchResultsTableViewController {

        viewController.searchManager = searchManager

        // replace the current Nav VC stack with the new SearchResultsTableViewController
        self.navigationController.setViewControllers([viewController], animated: false)

    }
}

Answer 2

为了防止出现导航栏控制器和出现 tableView 之间的延迟，请查看以下内容。

导航栏消失 Change Root ViewController 然后重新赋值

Navigation Bar Disappears Change Root ViewController and then reassign

ios

uitableview

uinavigationcontroller

uinavigationbar

rootview