如果用户已经使用 facebook 登录，则使用 swift 调用 segue

Posted 2023-03-17

【中文标题】如果用户已经使用 facebook 登录，则使用 swift 调用 segue

【英文标题】：Calling segue with swift if user already logged in with facebook

【发布时间】：2016-04-11 13:29:40

【问题描述】：

我一直在关注本教程，了解如何使用 swift 进行 facebook 登录。 http://letsbuildthatapp.com/2016/03/26/swift-facebook-login-sdk-and-getting-users-email/

但是，当我通过双击主页按钮并向上滑动应用程序来关闭应用程序时，我看到我的登录屏幕有一个不同之处。按钮的文本已更改为注销。

我想要做的是自动跳过该登录页面并执行此 segue：self.performSegueWithIdentifier("redirectAfterLogin", sender: self)

我遇到了这篇文章，但我自己无法解决这个问题，现在我有点困惑。 How to check if user is logged in with FBSDKLoginKit in ios?

您可以在下面看到我的 AppDelegate.swift 和 LoginVC.swift 文件。我该如何解决这个问题？

AppDelegate.swift

import UIKit



@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate, CNPPopupControllerDelegate 

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool 
        // Override point for customization after application launch.
        FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)

        return true
    

    func application(application: UIApplication, openURL url: NSURL, sourceApplication: String?, annotation: AnyObject) -> Bool 
        return FBSDKApplicationDelegate.sharedInstance().application(application, openURL: url, sourceApplication: sourceApplication, annotation: annotation)
    

    func applicationWillResignActive(application: UIApplication) 
        // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
        // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
    

    func applicationDidEnterBackground(application: UIApplication) 
        // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
        // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    

    func applicationWillEnterForeground(application: UIApplication) 
        // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
    

    func applicationDidBecomeActive(application: UIApplication) 
        // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.

    

    func applicationWillTerminate(application: UIApplication) 
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    

LoginVC.swift

import UIKit
import KASlideShow


class LoginVC: UIViewController, KASlideShowDelegate, FBSDKLoginButtonDelegate  

    let loginButton: FBSDKLoginButton = 
        let button = FBSDKLoginButton()
        button.readPermissions = ["email"]
        return button
    ()

    override func viewDidLoad() 
        super.viewDidLoad()
        // do stuff here

        view.addSubview(loginButton)
        loginButton.center = view.center
        loginButton.readPermissions = ["public_profile", "email", "user_friends"]
        loginButton.delegate = self // Remember to set the delegate of the loginButton

        if let token = FBSDKAccessToken.currentAccessToken() 
            fetchProfile()
        

        if FBSDKAccessToken.currentAccessToken() != nil 
            print("1")
            self.performSegueWithIdentifier("redirectAfterLogin", sender: self)
        


    

    func fetchProfile()
        print("fetching profile..")
        let params = ["fields": "email, first_name, last_name, picture.type(large)"]
        FBSDKGraphRequest(graphpath: "me", parameters: params).startWithCompletionHandler (connection, result, var error) -> Void in
            if error != nil 
                print (error)
                return
            

            if let email = result["email"] as? String 
                print(email)
                NSUserDefaults.standardUserDefaults().setObject(email, forKey: "email")
            

            if let first_name = result["first_name"] as? String 
                print(first_name)
                NSUserDefaults.standardUserDefaults().setObject(first_name, forKey: "first_name")
            

            if let last_name = result["last_name"] as? String 
                print(last_name)
                NSUserDefaults.standardUserDefaults().setObject(last_name, forKey: "last_name")
            

            if let picture = result["picture"] as? NSDictionary, data=picture["data"] as? NSDictionary, url=data["url"] as? String 
                print(url)
                NSUserDefaults.standardUserDefaults().setObject(url, forKey: "url")
            

            NSUserDefaults.standardUserDefaults().synchronize()
            print(result) // this prints whole FBSDKGraphRequest API response
        

    

    func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) 
        print("login completed")
        fetchProfile()
        self.performSegueWithIdentifier("redirectAfterLogin", sender: self)
    

    func loginButtonDidLogOut(loginButton: FBSDKLoginButton!) 

    

    func loginButtonWillLogin(loginButton: FBSDKLoginButton!) -> Bool 
        return true
    


    override func didReceiveMemoryWarning() 
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    

【参考方案1】：

你需要做的是在appDelegate上

application(application: UIApplication, didFinishLaunchingWithOptions launchOptions:

if let root = UIApplication.sharedApplication().windows[0].rootViewController as? UINavigationController 
     if CONDITION 
          root.viewControllers = [USER_HOMEPAGE]
      else 
          root.viewControllers = [USER_LOGIN]
     

【讨论】：

条件是如果用户已经登录，我假设你在 NSUserDefaults 中保留了 FB 登录密钥或其他东西？检查它是否存在？如果用户已经登录，则 USER_HOMEPAGE 将是用户所在的页面，该页面将通过“redirectAfterLogin”segue 显示。