ios - 连接到标签栏 View Controller

Question

我一直在按照教程创建待办事项列表。我有一个选项卡栏 View Controller 已经管理 2 组 TableView Controller (WeekAViewController - 项目 #1 和 WeekBViewController - 项目 2)。

现在，当我将选项卡栏 View Controller 连接到 AllListsViewController(成为我的第三组或项目 - 代码在下面)时，我在调试窗口中收到以下消息，指向我的 AppDelegate:

无法将“UITabBarController”(0x1ad56a0) 类型的值转换为“UINavigationController”(0x1ad5678)。(lldb)

请问我该如何解决这个问题？ (下面的 App Delegate 代码)

谢谢

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    let dataModel = DataModel()


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        let navigationController = window!.rootViewController as! UINavigationController
        let controller = navigationController.viewControllers[0] as! AllListsViewController
        controller.dataModel = dataModel

        return true
    }

    ...

    func applicationDidEnterBackground(application: UIApplication) {
        saveData()
    }

    ...

    func applicationWillTerminate(application: UIApplication) {
        saveData()
    }

    func saveData() {
        dataModel.saveChecklists()
    }

}

Answer 1

尝试一下并将其放入您的application(_:didFinishLaunchingWithOptions:)(提示位于代码注释中):

// first find the UITabBarController
let tabBarController = window!.rootViewController as! UITabBarController

// then look at its viewControllers array
if let tabBarViewControllers = tabBarController.viewControllers {
    // the reference to the AllListsViewController object
    let allListsViewController = tabBarViewControllers[0] as! AllListsViewController
    allListsViewController.dataModel = dataModel
}

编辑评论(代码评论中有提示):

// first find the UITabBarController
let tabBarController = window!.rootViewController as! UITabBarController

// then look at its viewControllers array
if let tabBarViewControllers = tabBarController.viewControllers {

    // your AllListsViewController is in a NavigationController so get the right NavigationController
    // you can see the order of your added NavigationControllers in your storyboard in your case its the third
    // because tabBarViewControllers is an array the NavigationController where your AllListsViewController is, is at index 2
    let navigationController = tabBarViewControllers[2] as! UINavigationController

    // after you get the right NavigationController get the reference to your AllListsViewController
    let allListsViewController = navigationController.viewControllers[0] as! AllListsViewController
    allListsViewController.dataModel = dataModel
}