Swift Firebase Facebook login dialog box pop up 2 times

Question

I have a facebook login which using firebase to authenticate the process. However, after I input my login detail and press confirm. It will back to the login page and pop up the facebook login page again. Then I press confirm again. It will display "User Cancel Login".

I am not sure why does it happen 2 times also when i click the confirm button it will display "User Cancel Login"

  func loginButton(FbLoginBtn: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!) {
    let FbloginManager = FBSDKLoginManager()
    FbloginManager.logInWithReadPermissions(["email","public_profile", "user_location", "user_hometown","user_friends"],fromViewController: self, handler: { (result, error) in


    if let error = error {
        print(error.localizedDescription)
            return
    }else if(result.isCancelled) {

        print("User Cancel Login")

    }else{
        let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)
       print("User\(self.user?.displayName) login successful")
        AppState.instance.signedIn = true
        if AppState.instance.signedIn == false{
        self.firebaseLogin(credential)
        //self.createFirebaseUser()
        self.performSegueWithIdentifier(SEGUE_LOGIN, sender: nil)
    }
    }
    })
}

Answer 1

For me this code work :

@IBAction func btnFBLoginPressed(sender: AnyObject) {

    self.comeFromFB = true

    let fbLoginManager : FBSDKLoginManager = FBSDKLoginManager()

    var id:String = ""
    var urlPhoto:String = ""

    fbLoginManager.logInWithReadPermissions(["email"], fromViewController: self){ (result, error) -> Void in
        if let error = error
        {
            print(error)
            return
        }
        else
        {
            let fbloginresult : FBSDKLoginManagerLoginResult = result
            if (!result.isCancelled)
            {
                if(fbloginresult.grantedPermissions.contains("email"))
                {
                    if((FBSDKAccessToken.currentAccessToken()) != nil){
                        FBSDKGraphRequest(graphPath: "me", parameters: ["fields": "id, name, first_name, last_name, picture.type(large), email"]).startWithCompletionHandler({ (connection, result, error) -> Void in

                            let bUserFacebookDict = result as! NSDictionary

                            id = bUserFacebookDict["id"]! as! String
                            urlPhoto = "https://graph.facebook.com/"+id+"/picture?width=500&height=500"

                            let credential = FIRFacebookAuthProvider.credentialWithAccessToken(FBSDKAccessToken.currentAccessToken().tokenString)
                            FIRAuth.auth()?.signInWithCredential(credential) { (user, error) in

                            self.currentUser.setCurrentUserState(user!.uid, _firstName: bUserFacebookDict["first_name"]! as! String, _name: bUserFacebookDict["last_name"]! as! String, _urlPhoto: urlPhoto, _email:bUserFacebookDict["email"]! as! String, _connected:true)


                            }
                        })
                    }
                }
            }

        }
    }
}

Then I add a listener in the ViewDidAppear method with perform segue after "connected" state.