使用SOAP API

Question

我想使用SOAP API，但我遇到了问题。

我的委托方法未被调用，URL变量显示无法读取NSURL类型的数据。

import UIKit

class ViewController: UIViewController, UITextFieldDelegate, NSURLConnectionDelegate, XMLParserDelegate {

    var mutableData:NSMutableData  = NSMutableData.init()
    var currentElementName:NSString = ""



    @IBOutlet var txtCelsius : UITextField!
    @IBOutlet var txtFahrenheit : UITextField!
      override func viewDidLoad() {
        super.viewDidLoad()
        let celcius = "24"
        let soapMessage = "<?xml version='1.0' encoding='utf-8'?><soap:Envelope xmlns:xsi='https://www.w3.org/2001/XMLSchema-instance' xmlns:xsd='https://www.w3.org/2001/XMLSchema' xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'><soap:Body><CelsiusToFahrenheit xmlns='https://www.w3schools.com/xml/'><Celsius>\(String(describing: celcius))</Celsius></CelsiusToFahrenheit></soap:Body></soap:Envelope>"
        let urlString = "https://www.w3schools.com/xml/tempconvert.asmx"
          print(urlString)
        if let url = NSURL(string: urlString)
        {
            print(url)
            let theRequest = NSMutableURLRequest(url: url as URL)
            theRequest.addValue("text/xml; charset=utf-8", forHTTPHeaderField: "Content-Type")
            theRequest.addValue((soapMessage), forHTTPHeaderField: "Content-Length")
            theRequest.httpMethod = "POST"
            theRequest.httpBody = soapMessage.data(using: String.Encoding.utf8, allowLossyConversion: false)
            let connection = NSURLConnection(request: theRequest as URLRequest, delegate: self, startImmediately: true)
            connection!.start()
        }
    }

      private func connection(connection: NSURLConnection!, didReceiveResponse response: URLResponse!) {
        mutableData.length = 0;
    }

     private func connection(connection: NSURLConnection!, didReceiveData data: NSData!) {
        mutableData.append(data as Data)
    }


    func connectionDidFinishLoading(connection: NSURLConnection!) {
        let xmlParser = XMLParser(data: mutableData as Data)
        xmlParser.delegate = self
        xmlParser.parse()
        xmlParser.shouldResolveExternalEntities = true

    }


    func parser(_ parser: XMLParser, foundCharacters string: String)
    {
        if currentElementName == "CelsiusToFahrenheit"
        {
            txtFahrenheit.text = string
        }
    }
}