如何检查用户是否已登录以及是否未重定向到登录屏幕 [英] How to check if a user is logged in and if not redirect to the login screen

问题描述

我的登录屏幕嵌入在UINavigationController中，而主页屏幕嵌入在UITabBarController中.

I have my login screen embedded in a UINavigationController and my home page screen embedded in a UITabBarController.

我的登录页面已通过编程方式完成，并且使用storyboards创建了TabBarController.在AppDelegate.swift文件中，将登录屏幕设置为rootViewController.

My login page was done programmatically and TabBarController was created using storyboards. In AppDelegate.swift file I made the the login screen the rootViewController.

但是现在我想检查用户是否已登录并将TabBarController设置为rootViewController，如果用户未登录，请重定向至登录屏幕，然后选择TabBarController和将其设置为rootViewController.

But now I want to check if the user is logged in and make the TabBarController the rootViewController, and if the user isn't logged in, redirect to the login screen, then segue to the TabBarController and make it the rootViewController.

服务器通过向客户端发送令牌来对用户进行身份验证.我是否使用NSUserDefaults存储令牌?我是否应该检查用户是否具有_token _作为验证用户是否已登录的方法?

The server authenticates the user by sending a token to the client. Do I store the token using NSUserDefaults? Should I check if the user has _token_ as a way to validate if the user is logged in?

推荐答案

由于您是以编程方式创建LoginViewController的，因此我假定TabBarController默认为storyboard的rootViewController.您在AppDelegate中所需要做的就是这个.

Since you are creating your LoginViewController programatically so I assume that the TabBarController would be the rootViewController of the storyboard by default. All you need to do in your AppDelegate is this.

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

    let token = UserDefaults.standard.object(forKey: "token")
    if token == nil {
        //***************
        //Create your LoginViewController and make it the rootViewController
        //***************
    }
    return true
}

注意:我使用的是Swift 3，因此语法上会有细微的差别.

Note: I'm using Swift 3 so there will be a slight difference in the syntax.

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