Swift中针对Planet XML的XML解析

如何解决Swift中针对Planet XML的XML解析

在UI上单击按钮时，当前输出为空数组或[]，以及一个类似于Optional(1337 bytes)的可选内容。这来自代码print(self.result)和print(data)。我感到困惑的是，我打电话给print(self.result)之后该怎么办。我实际上如何解析传入的数据？感谢您的提前帮助。

注意：UI仅有一个按钮，可触发查找功能和两个文本字段。

预期结果：当按钮触发时，我可以访问xml数据以放入UI的文本字段中。目标数据是行星的名称和直径km。

更新11/9/20：将委托函数移至查找函数后未返回任何结果

行星xml

<planet name="Mercury" moonCount="0" distanceFromSun="0.39" diameterKm="4878"> </planet>
<planet name="Venus" moonCount="0" distanceFromSun="0.72" diameterKm="12104"> </planet>
<planet name="Earth" moonCount="1" distanceFromSun="1" diameterKm="12756"> </planet>
<planet name="Mars" moonCount="2" distanceFromSun="1.52" diameterKm="6787">
...
</planet>
<planet name="Jupiter" moonCount="63" distanceFromSun="5.2" diameterKm="142800">
<satellite name="Io" diameterKm="3630"/>
<satellite name="Europa" diameterKm="3138"/>
<satellite name="Ganymede" diameterKm="5262"/>
<satellite name="Callisto" diameterKm="4800"/>
</planet>
<planet name="Saturn" moonCount="62" distanceFromSun="9.54" diameterKm="120000"> </planet>
<planet name="Uranus" moonCount="27" distanceFromSun="19.8" diameterKm="51118"> </planet>
<planet name="Neptune" moonCount="13" distanceFromSun="30.06" diameterKm="49528"> </planet>
<dwarfPlanet name="Pluto" moonCount="3" distanceFromSun="39.44" diameterKm="2300">
<satellite name="Charon" diameterKm="1207"/>
</dwarfPlanet>
<dwarfPlanet name="Ceres" moonCount="0" distanceFromSun="2.76" diameterKm="974.6"> </dwarfPlanet>
<dwarfPlanet name="Eris" moonCount="1" distanceFromSun="67.67" diameterKm="3000"> </dwarfPlanet>
</planets>

ViewController

//  ViewController.swift
//  Project 5
//
//  Created by Gracias Claude on 11/8/20.
//

import UIKit

class ViewController: UIViewController,XMLParserDelegate {
    var results: [[String: String]]?         // the whole array of dictionaries
    var currentDictionary: [String: String]? // the current dictionary
    var currentValue: String?
    
    let recordKey = "planets"
    let dictionaryKeys = Set<String>(["planet"])
    @IBOutlet weak var Name: UITextField!
    @IBOutlet weak var diameterText: UITextField!
    var downloader = Downloader();
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    @IBAction func find(_ sender: Any) {
        //saves the data to a file
//        if var URL = NSURL(string: "http:universe.tc.uvu.edu/cs3680/project/p5/planets.xml") {
//            Downloader.load(URL: URL)
//             }
        
//        downloader.getXml(url:"http:universe.tc.uvu.edu/cs3680/project/p5/planets.xml")
//    }
        let request = NSMutableURLRequest(url: NSURL(string: "http:universe.tc.uvu.edu/cs3680/project/p5/planets.xml")! as URL,cachePolicy: .useProtocolCachePolicy,timeoutInterval: 10.0)
          request.httpMethod = "GET"

          let session = URLSession.shared
          let dataTask = session.dataTask(with: request as URLRequest,completionHandler: { (data,response,error) -> Void in
              if (error != nil) {
                  print(error!)
              } else {
                  let httpResponse = response as? HTTPURLResponse
                  //print(httpResponse!)
                print(data)
                let parser = XMLParser.init(data: data!)
                parser.delegate = self
                if parser.parse() {
                     print(self.results ?? "No results")
                 }
              }
          })
          dataTask.resume()
    }
    
    func parserDidStartDocument(_ parser: XMLParser) {
           results = []
       }
    
    func parser(_ parser: XMLParser,didStartElement elementName: String,namespaceURI: String?,qualifiedName qName: String?,attributes attributeDict: [String : String]) {
           if elementName == recordKey {
               currentDictionary = [:]
           } else if dictionaryKeys.contains(elementName) {
               currentValue = ""
           }
       }
    
    func parser(_ parser: XMLParser,parseErrorOccurred parseError: Error) {
           print(parseError)

           currentValue = nil
           currentDictionary = nil
           results = nil
       }
    
    

}