如何在成功登录后更改初始视图控制器？

Question

我正在开发我的第一个应用程序，我无法理解如何在用户成功登录后使用NSUserDefaults更改我的初始视图控制器。（一旦用户成功登录，用户将不再需要在启动应用程序后登录）我已经阅读了其他帖子和google教程，但老实说我无法理解它们。

我主要是格式问题。

编辑：

这是我尝试添加的新代码：

 self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        var initialViewController: UIViewController



        if PFUser.currentUser() != nil {

            initialViewController = mainStoryboard.instantiateViewControllerWithIdentifier("Timeline") as! UIViewController
        }else {

            initialViewController = mainStoryboard.instantiateViewControllerWithIdentifier("LoginView") as! LoginViewController
        }

            self.window?.rootViewController = initialViewController

        self.window?.makeKeyAndVisible()

但是，每次我尝试启动应用程序时，它都会立即崩溃。错误说明：

2015-08-19 10:30:23.966 Venddy[3451:95841] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** setObjectForKey: key cannot be nil'

如果有人能给我建议，我将不胜感激。我是应用程序开发的新手。谢谢！

Answer 1

你应该在AppDelegate.swift文件里面的didFinishLaunchingWithOptions文件中设置它。

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

   //SET INITIAL CONTROLLER
    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    var initialViewController: UIViewController
    let userDefaults = NSUserDefaults.standardUserDefaults()

    if let login = userDefaults.objectForKey("loginSuccess") as! Bool //your condition if user is already logged in or not
    {
       // if already logged in then redirect to MainViewController

        initialViewController = mainStoryboard.instantiateViewControllerWithIdentifier("MainController") as! MainViewController // 'MainController' is the storyboard id of MainViewController 
    }
    else
    {
       //If not logged in then show LoginViewController
        initialViewController = mainStoryboard.instantiateViewControllerWithIdentifier("LoginController") as! LoginViewController // 'LoginController' is the storyboard id of LoginViewController 

    }

    self.window?.rootViewController = initialViewController

    self.window?.makeKeyAndVisible()
 return true
} 

希望这会有所帮助！

Answer 2

你可以这样做

您只需将LoginSignup视图控制器添加到故事板，然后将“Storyboard Id”设置为“loginVC”。之后，在application：didFinishLaunchingWithOptions中检查用户是否登录。

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

    let storyboard = UIStoryboard(name: "Main", bundle: NSBundle.mainBundle())
    let logined = ?
    var vc: UIViewController?
    if !logined {
        vc = storyboard.instantiateViewControllerWithIdentifier("loginVC")
    } else {
        vc = storyboard.instantiateInitialViewController()
    }
    window = UIWindow(frame: UIScreen.mainScreen().bounds)
    window?.rootViewController = vc
    window?.makeKeyAndVisible()
    return true
}

不要忘记在“部署信息”中的目标设置中删除“主界面”的值

Answer 3

代码为Swift 4.2和5代码：

           self.window = UIWindow(frame: UIScreen.main.bounds)

           if(loggedIn){

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

            let initialViewController = storyboard.instantiateViewController(withIdentifier: "dashboardVC")

            } else {

            let storyboard = UIStoryboard(name: "Login", bundle: nil)
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            let initialViewController = storyboard.instantiateViewController(withIdentifier: "loginVC")
            }
            self.window?.rootViewController = initialViewController
            self.window?.makeKeyAndVisible()