如何在应用程序委托中为TabView Controller标签设置属性

Question

我需要在控制器上设置一个属性，这是在应用程序委托中进行的设置。在上一个使用导航栏的任务中，此方法有效：

（我要设置属性的控制器不是根控制器，而是第三个选项卡，如果有帮助的话）

func application(_ application: UIApplication, didFinishLaunchingWithOptions
        launchOptions: [UIApplicationLaunchOptionsKey : Any]?) -> Bool {
    // Override point for customization after application launch.
    // Create an ItemStore
    let itemStore = ItemStore()
    // Access the ItemsViewController and set its item store
    let itemsController = window!.rootViewController as! ItemsViewController
    itemsController.itemStore = itemStore
return true }

但是，创建类似的程序时，我需要使用选项卡栏，但无法使其正常工作并继续遇到上述错误， 让editcontroller = tabcontroller。 -线

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool
    {
        // Override point for customization after application launch.
        // Create an pindatabase
        let pinDataBase = PinDatabase()

        // Access the ContactsViewController and set its contact store
        let tabController = window!.rootViewController as! UITabBarController
        let editController = tabController.tabBar as! EditViewController
        editController.pinDataBase = pinDataBase

        return true

    }

任何帮助将不胜感激