斯威夫特：我必须调用 Facebook 登录按钮两次才能获得 FBSDKAccessToken

Posted 2023-03-17

【中文标题】斯威夫特：我必须调用 Facebook 登录按钮两次才能获得 FBSDKAccessToken

【英文标题】：Swift: I have to call Facebook loginbutton twice to get an FBSDKAccessToken

【发布时间】：2016-04-30 09:53:14

【问题描述】：

我的问题是：我必须按两次 Facebook 登录按钮才能获得 FBSDKAccessToken。之后，令牌在应用程序的整个使用过程中都是持久的。在第一次按下按钮时，AccessToken 似乎在那里，并且在观察者被调用四次后再次“消失”。

当我将观察者移动到我的 viewDidAppear() 并且取消注释 'FBSDKProfile.enableUpdatesOnAccessTokenChange(true)' 行时，也会发生同样的情况。

我有以下代码： 在我的 AppDelegate 中：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool 
    // Let Facebook API know we finished launching         
    FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions)
    return true


func applicationDidBecomeActive(application: UIApplication) 
    // Register actions, such as add clicks and app FB statistics
    FBSDKAppEvents.activateApp()


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

在我的 LoginOrSignupViewController 中

class LoginOrSignupViewController: UIViewController, FBSDKLoginButtonDelegate 

@IBOutlet weak var buttonFacebooklogin: FBSDKLoginButton!

override func viewDidLoad() 
    super.viewDidLoad()

    // Customize the facebookLogin button   
    buttonFacebooklogin.readPermissions = ["public_profile", "email", "user_friends"]
    buttonFacebooklogin.delegate = self
    //FBSDKProfile.enableUpdatesOnAccessTokenChange(true)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(listenForFBLogin), name: FBSDKAccessTokenDidChangeNotification, object: nil)

在我的 viewDidAppear() 中，我有一些打印语句。以及在我的 Facebook 登录按钮中。我注意到 Observer 函数被调用了 4 次，前两次有一个 AccessToken，最后两次没有。

当我再次按下 Facebook 登录按钮时，它的行为就像它应该的那样。 打印语句：

第一次按下登录按钮：

Observer listenForFBLogin function...
We got a token here...
<FBSDKAccessToken: 0x7fa0896b5f40>
Observer listenForFBLogin function...
We got a token here...
<FBSDKAccessToken: 0x7fa0896b5f40>
Observer listenForFBLogin function...
Even in the listenForFBLogin the Accestoken is empty...
Observer listenForFBLogin function...
Even in the listenForFBLogin the Accestoken is empty...
User is not logged in...

我第二次按下登录按钮：

Observer listenForFBLogin function...
We got a token here...
<FBSDKAccessToken: 0x7fa08b8407b0>
Observer listenForFBLogin function...
We got a token here...
<FBSDKAccessToken: 0x7fa08b8407b0>
Tickee isUserLoggedIn: Logged in with Facebook and Firebase...
User is logged in, go to the tabbar...

我的 Facebook 登录代码

func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) 

    if error != nil 
        // Error login
        NSLog("Error van loginButton func:")
        NSLog(error.localizedDescription)
     else if result.isCancelled 
        // User cancelled login
        // NSLog("User cancelled Facebook login")
     else 

        // User logged in. Proceed to request Auth from Firebase

        // Signup or Login with Firebase
        let firebaseRef = Firebase(url: "https://tickee.firebaseio.com/")
        let accessToken = FBSDKAccessToken.currentAccessToken().tokenString

        // Auth the User in Firebase
        firebaseRef.authWithOAuthProvider("facebook", token: accessToken, withCompletionBlock: 
            (error, authData) in

            if (error != nil) 
                NSLog("Login failed")
             else 

                // Check if UID is saved to UserDefaults
                let userUID = self.tickee.getUserUIDFromUserDefaults()

                // Check if UID exists
                if userUID == nil 

                    // UID doesn't not exists, there is no user
                    print("User doesn't exist yet, create new Facebook user in Firebase...")

                    // Create User in Firebase
                    self.tickee.createUserInFirebase("facebook", nameField: nil)

                    // Save UID in NSUserDefaults
                    self.tickee.saveUserUIDtoNSUserDefaults()
                 else 
                    print("User exists already, no need to create one again...")
                

                print("Done loggin in, now wait for the observer...")

            
        )
    

【参考方案1】：

在 viewDidLoad() 中，我询问了视图用户是否已登录。使用 Facebook 登录和使用 Firebase 进行身份验证时，有几个异步函数。结果尚未正确处理，因此 viewDidLoad 很快就会调用。

在登录函数本身加载完成后，我删除了对结果的处理，不再在 viewDidLoad() 中