我在我的应用程序中集成了Facebook。但登录FBSDKAccessToken后。currentAccessToken（）发现为零。
下面是我的代码：

override func viewDidLoad() {

    if (FBSDKAccessToken.currentAccessToken() != nil)
    {
        print("Not loggedin...")
    }
    else
    {
        print("logged in...")
    }

    loginbutton.delegate = self
    loginbutton.readPermissions = ["public_profile", "email", "user_friends"]
}

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

    if(error == nil)
    {
        print("login complete")
        print(result)
        print(result.grantedPermissions)
    }
    else{
        print(error.localizedDescription)
    }

    if let userToken = result.token
    {
        let token:FBSDKAccessToken = result.token
        print("TOKEN = \(FBSDKAccessToken.currentAccessToken().tokenString)")
        print("User ID = \(FBSDKAccessToken.currentAccessToken().userID)")
    }

    let graphRequest : FBSDKGraphRequest = FBSDKGraphRequest(graphPath: "me", parameters: ["fields":"name, email"])

    graphRequest.startWithCompletionHandler({ (connection, result, error) -> Void in

        if ((error) != nil)
        {
            // Process error
            print("Error: \(error)")
        }
        else
        {
            print("fetched user: \(result)")
            let userEmail : NSString = result.valueForKey("email") as! NSString
            print("User Email is: \(userEmail)")
            let userName : NSString = result.valueForKey("name") as! NSString
            print("User Name is: \(userName)")
        }
    })
}

func loginButtonDidLogOut(loginButton: FBSDKLoginButton!) {
    print("User Logged Out")
}

登录后，我得到一个空白屏幕。它打印登录成功的消息，但它不是进入这个：

if let userToken = result.token
{
    let token:FBSDKAccessToken = result.token
    print("TOKEN = \(FBSDKAccessToken.currentAccessToken().tokenString)")
    print("User ID = \(FBSDKAccessToken.currentAccessToken().userID)")
}

所以，我没有得到任何令牌。而它去打印电子邮件它显示这个错误：
这是我在appdelegate中代码

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

func applicationDidBecomeActive(application: UIApplication) {

    FBSDKAppEvents.activateApp()
}

func application(application: UIApplication,
    openURL url: NSURL, options options: [String: AnyObject]) -> Bool {
        return GIDSignIn.sharedInstance().handleURL(url,
            sourceApplication: options[UIApplicationOpenURLOptionsSourceApplicationKey]! as! String,
            annotation: options[UIApplicationOpenURLOptionsAnnotationKey])
}

实际上每次它调用的openurl方法的gmail集成，所以我怎么能把条件调用的方法的facebook集成