Question

如果用户名= = nil，我想在tabbar中更改 viewControllers 。

我有两个可以更改的viewControllers：

1） ProfileVC

2） SignInVC

但是当我的应用程序启动时，用户会看到不同的viewController，他是 NewsVC 。

我需要在运行应用程序之前进行检查，并在tabbar中替换viewController。

在AppDelegate.swift中大致如此：

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

    if Auth.auth().currentUser != nil {
        let profileVC = storyboard.instantiateViewController(withIdentifier: "ProfileVC")
        window?.rootViewController = profileVC
    } else {
        let loginVC = storyboard.instantiateViewController(withIdentifier: "SignInVC")
        window?.rootViewController = loginVC
    }
}

但这不正确。我怎么改变索引或viewController？

Answer 1

您需要继承UITabBarController并管理它的viewControllers数组

class MainTabBarController: UITabBarController {

    override func awakeFromNib() {
        super.awakeFromNib()

       // if you will say force - unwrapped it's the developer job to keep track here          

        let signUp = self.viewControllers![0]

        let profile = self.viewControllers![1]

        let newsFeeds = self.viewControllers![2]

        if user == nil {

            self.viewControllers = [signUp] // leave signup only

        }

    }


}

将MainTabBarController分配给IB

中的标签

Answer 2

您需要为viewcontroller设置索引。

这是你以编程方式执行的方式：

    self.window = UIWindow(frame: UIScreen.main.bounds)
    let nav1 = UINavigationController()
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let profileVC = mainStoryboard.instantiateViewController(withIdentifier: "ProfileVC") as! //your VC
    nav1.viewControllers = [profileVC]

    let nav2 = UINavigationController()
    let loginVC = mainStoryboard.instantiateViewController(withIdentifier: "SignInVC") as! //Your VC 
    nav2.viewControllers = [loginVC]

    let tabController = UITabBarController()
    tabController.viewControllers = [profileVC, loginVC]
    tabController.selectedIndex = 0 //This line will solve your question & take you to the profileVC
    self.window!.rootViewController =  tabController
    self.window?.makeKeyAndVisible()

应用程序启动时更改tabbarindex或setviewcontroller

2 个答案: