UITabBarController 仅显示第一个选项卡

Question

我重新提出这个问题是因为 UITabbarController showing only first tab 中的问题没有得到回答...我不明白为什么我的 UITabBarController 只显示第一个选项卡。

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window?.backgroundColor = UIColor.darkGray
        self.window?.makeKeyAndVisible()
        let tab = UITabBarController()
        let v1 = VC1(nibName: "View1", bundle: nil)
        let v2 = VC2(nibName: "View2", bundle: nil)
        let v3 = VC3(nibName: "View3", bundle: nil)
        let myViews = [v1,v2,v3]
        tab.viewControllers = myViews
        self.window?.rootViewController = tab 
        return true
    }

}

VC1代码：

class VC1: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        print("view 1 will load")
        self.title = "View 1"
        // Do any additional setup after loading the view.
    }

}

class VC2:

class VC1: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        print("view 2 will load")
        self.title = "View 2"
        // Do any additional setup after loading the view.
    }

}

VC3:

class VC1: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        print("view 3 will load")
        self.title = "View 3"
        // Do any additional setup after loading the view.
    }

}

我认为这是一种经过测试和验证的创建选项卡的方法，但它似乎不起作用，这是结果截图

Answer 1

我找到了一种更简洁的实现方法，View Controller 的标题是属性并且可以在实例化后立即设置

因此更新后的代码如下所示：

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window?.backgroundColor = UIColor.darkGray
        self.window?.makeKeyAndVisible()
        let tab = UITabBarController()
        let v1 = VC1(nibName: "View1", bundle: nil)
        let v2 = VC2(nibName: "View2", bundle: nil)
        let v3 = VC3(nibName: "View3", bundle: nil)
        v1.title = "View 1"
        v2.title = "View 2"
        v3.title = "View 3"
        let myViews = [v1,v2,v3]
        tab.setViewControllers(myViews, animated: false)
        self.window?.rootViewController = tab 
        return true
    }

}

屏幕截图是：

Answer 2

UITabBarController 使用来自每个视图控制器的 title 来创建显示在屏幕上的标签。这里的问题是，在调用 viewDidLoad 之前，您的视图控制器对 title 属性没有任何价值，但为时已晚。

您应该在初始化期间设置 title 属性； initWithNibName:bundle: 是个好地方。

UITabBarController 仅显示第一个选项卡

UITabBarController showing only the first tab

swift

tvos