在初始化Xcode错误期间无法成功更新网络信息

Question

我一直在努力完成以下程序执行，目前我正在使用Xcode 8和Swift 3 ...它只是一个简单的登录程序，但只要应用程序运行，控制台就会打印错误＆＃34;无法执行在初始化期间成功更新网络信息＆＃34;甚至在点击登录按钮之前，解决方案就非常少，而且没有一个能为我工作。

import UIKit
import FBSDKCoreKit
import FBSDKLoginKit
class ViewController: UIViewController, FBSDKLoginButtonDelegate {
    @IBOutlet weak var btnButton: FBSDKLoginButton!     
    override func viewDidLoad() {
     super.viewDidLoad()
                 // Do any additional setup after loading the view, typically from a nib.
    }
 override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
func loginButton(_ loginButton: FBSDKLoginButton!, didCompleteWith result: FBSDKLoginManagerLoginResult!, error: Error!)
        {
                if error == nil
                {
                   print("login Successful")
                   self.configureFacebook() 
                }
                else
                {
                    print("error\(error!)")
                }
               }
func loginButtonDidLogOut(_ loginButton: FBSDKLoginButton!)
        {
            let loginManager: FBSDKLoginManager = FBSDKLoginManager()
            loginManager.logOut()
            print("logout successful")    
        }
func configureFacebook()
        {
            btnButton.readPermissions = ["public_profile", "email", "user_friends"];
            btnButton.delegate = self         
    }
}