问抛出函数类型(_，_，_)到非抛出函数类型(Data?，Response?，URLResponse?)的转换无效空洞

EN

import UIKit

class loginViewController: UIViewController {

    @IBOutlet weak var userLoginTextField: UITextField!
    @IBOutlet weak var userPasswordTextField: UITextField!


    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func loginButtonTapped(_ sender: Any) {

        let user_login = userLoginTextField.text;
        let user_passwd = userPasswordTextField.text;

        if((user_passwd?.isEmpty)! || (user_passwd?.isEmpty)!) { return; }

        //Send user data to server
        let myUrl = NSURL(string: "https://www.pcpusa.net/legacy/iOS/userLogin.php");
        var request = URLRequest(url: myUrl! as URL);
        request.httpMethod = "POST";

        let postString = "login=\(String(describing: user_login))&password=\(String(describing: user_passwd))";

        request.httpBody = postString.data(using: String.Encoding.utf8);

        **let task = URLSession.shared.dataTask(with: request){**
            data,response,error in
            if error != nil {
                print("error=\(String(describing: error))")
                return
            }

            var err: NSError?
            var json = try JSONSerialization.JSONObjectWithData(data, options: .mutableContainers, error: &err) as? NSDictionary

            if let parseJSON = json {
                var resultValue:String = parseJSON["status"] as String!;
                print("result: \(resultValue)")

                if(resultValue=="Success")
                {

                    //Login is successful
                    NSUserDefaults.standardUserDefaults().setBool(true, value(forKey: "isUserLoggedIn"));
                    NSUserDefaults.standardUserDefaults().synchronize();

                    self.dismissViewControllerAnimated(true, completion:nil);

                }

            }

        }
        task.resume()
    }
}