EWS / Exchange.asmx返回错误代码401

Question

我正在尝试使用swift实现GetItem operation但它总是返回401.以下是代码片段。目前正在getItem调用viewDidLoad。

func getItem() {
    let url = URL(string: "https://outlook.office365.com/EWS/Exchange.asmx")!
    let message = xmlString()
    let data = message.data(using: .utf8)
    var request = URLRequest(url: url)

    request.httpMethod = "POST"
    request.httpBody = data
    request.addValue("text/xml; charset=utf-8", forHTTPHeaderField: "Content-Type")
    request.addValue("\(data!.count)", forHTTPHeaderField: "Content-Length")

    let confirguration = URLSessionConfiguration.default
    let session = URLSession(configuration: confirguration, delegate: self, delegateQueue: OperationQueue.main)
    let task = session.dataTask(with: request) { (data, response, error) in
       print("Data: \(data!) ")
       print("Response: \(response!)")
    }
    task.resume()
}

func urlSession(_ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void) {
    let userName = "xxxxxxx"
    let password = "xxxxxxx"
    let credential = URLCredential(user: userName, password: password, persistence: .forSession)
    challenge.sender?.use(credential, for: challenge)
    completionHandler(URLSession.AuthChallengeDisposition.useCredential, URLCredential(trust: challenge.protectionSpace.serverTrust!))
}

控制台输出：

2018-04-07 20:30:50.559884+0530 Tapas_EWSGetItem[2562:80677] CredStore - performQuery - Error copying matching creds.  Error=-25300, query={
    class = inet;
    "m_Limit" = "m_LimitAll";
    ptcl = htps;
    "r_Attributes" = 1;
    sdmn = "";
    srvr = "outlook.office365.com";
    sync = syna;
}

Data: 0 bytes

Response: <NSHTTPURLResponse: 0x608000223a40> { URL: https://outlook.office365.com/EWS/Exchange.asmx } { Status Code: 401, Headers {
    "Content-Length" =     (
        0
    );
    Date =     (
        "Sat, 07 Apr 2018 15:00:44 GMT"
    );
    Server =     (
        "Microsoft-IIS/10.0"
    );
    "Www-Authenticate" =     (
        "Basic Realm=\"\""
    );
    "X-FEServer" =     (
        SG2PR06CA0201
    );
    "X-Powered-By" =     (
        "ASP.NET"
    );
    "request-id" =     (
        "7c7075b7-7496-4847-9418-d11e66a7c97f"
    );
} }

任何人都可以帮我弄清楚我做错了什么。提前谢谢。