ios - Swift:我必须调用 Facebook 登录按钮两次才能获取 FBSDKAccessToken

Question

我的问题是:我必须按 Facebook 登录按钮两次才能获取 FBSDKAccessToken。此后， token 在应用程序的整个使用过程中保持不变。第一次按下按钮时，AccessToken 似乎就在那里，并在观察者被调用四次后再次“消失”。

当我将观察者移动到 viewDidAppear() 并取消注释“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。以及我的 Facebook 登录按钮。我注意到 Observer 函数被调用了 4 次，前两次有 AccessToken，最后两次没有。

当我再次按下 Facebook 登录按钮时，它的表现就像它应该的那样。打印报表:

第一次按下登录按钮时:

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...

第二次按下登录按钮时:

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...")

            }
        })
    }
}

Answer 1

在 viewDidLoad() 中，我询问 View 用户是否已登录。使用 Facebook 登录并使用 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。

我在登录函数本身中删除了加载完成后对结果的处理，不再在 viewDidLoad() 中处理