斯威夫特XML解析器導致錯誤

Question

我試圖解析一個簡單的XML文件，但我不斷收到錯誤

「錯誤描述：（可可錯誤-1）操作無法完成 行號：0"

XML文件（名爲mathquiz.xml放置在一個文件夾，名爲IMG）：

<quiz> 
    <title> 
     Y1 Maths Quiz 
    </title> 
    <question> 
     <description> 
      What is 2+2 
     </description> 
     <answer> 
      4 
     </answer> 
     <answer> 
      3 
     </answer> 
     <answer> 
      2 
     </answer> 
     <answer> 
      1 
     </answer> 
    </question> 
</quiz> 

分析器：

// 
// QuizXMLParser.swift 
// MathQuiz 
// 
// Created by Raees on 22/06/2017. 
// Copyright © 2017 Raees Apps. All rights reserved. 
// 

import Foundation 

public class QuizXMLParser : NSObject, XMLParserDelegate { 

    var currentContent = "" 
    var quiz = Quiz() 
    var question = Question() 

    public func beginParsing(file url: String) { 
     guard let myURL = NSURL(string:url) else { 
      print("URL not defined properly") 
      return 
     } 
     guard let parser = XMLParser(contentsOf: myURL as URL) else { 
      print("Cannot Read Data") 
      return 
     } 
     parser.delegate = self 
     if !parser.parse(){ 
      print("Data Errors Exist:") 
      let error = parser.parserError! 
      print("Error Description:\(error.localizedDescription)") 
      print("Line number: \(parser.lineNumber)") 
     } 
    } 

    public func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]){ 
     print("Beginning tag: <\(elementName)>") 
     if elementName == "question" { 
      question = Question() 
     } 
     currentContent = "" 
    } 

    public func parser(_ parser: XMLParser, foundCharacters string: String){ 
     currentContent += string 
     print("Added to make \(currentContent)") 
    } 

    public func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?){ 
     print("ending tag: </\(elementName)> with contents:\(currentContent)") 
     switch elementName{ 
     case "question": 
      quiz.questions.append(question) 
      print ("model has \(question)") 
     case"title": 
      quiz.title = currentContent 
     case "description": 
      if let index = Int(currentContent) { 
       quiz.currentQuestionIndex = index 
      } 
     case "answer": 
      question.answers.append(currentContent) 
     default: 
      return 
     } 
    } 
} 

呼叫在視圖控制器解析器：

let parser = QuizXMLParser() 
parser.beginParsing(file: "img/mathquiz.xml") 

我怎樣才能使它成功地解析XML文件？我沒有看到任何問題。

Answer 1

首先，爲了讀取從包的內容的文件執行以下操作：

let parser = QuizXMLParser() 
    if let path = Bundle.main.url(forResource: "mathQuiz", withExtension: "xml") { 
     parser.beginParsing(file: path) 
    } 

，然後改變其功能beginParsing（文件網址：字符串）接受網址，而不是一個字符串。

public func beginParsing(file url: URL) { 
    guard let parser = XMLParser(contentsOf: url) else { 
     print("Cannot Read Data") 
     return 
    } 
    parser.delegate = self 
    if !parser.parse(){ 
     print("Data Errors Exist:") 
     let error = parser.parserError! 
     print("Error Description:\(error.localizedDescription)") 
     print("Line number: \(parser.lineNumber)") 
    } 
} 

這應該可以解決您的問題。