將方法外包給靜態方法時發生Swift錯誤

Question

我想開始用Swift編寫我的Android應用程序。應用程序應使用URL中的xml來顯示對象列表。

解析並顯示在UITableViewController已經在工作。現在我想將解析外包給一個靜態類，每當我想要獲取對象列表時，我都可以使用它。

問題是我得到一個EXC_BAD_ACCESS當我使用外包類錯誤。我認爲問題可能是，我試圖訪問已經釋放的內存，但我不確定。

下面你可以找到我使用的代碼：

XML（簡體）：

<result> 
    <row> 
     <id>1</id> 
     <name>Alpha</name> 
    </row> 
    <row> 
     <id>2</id> 
     <name>Beta</name> 
    </row> 
    <row> 
     <id>3</id> 
     <name>Gamma</name> 
    </row> 
</result> 

XMLHelper.swift（外包類，採用外包類ToolXMLParserDelegate.swift）：

import Foundation 

class XMLHelper : NSObject{ 

    static var baseURL = "{myServerUrl}" // not public for security reasons 
    static var toolListString = "getToolList.php" 

    class func getToolList() -> [Tool]? { 
     var toolList: [Tool] = [] 

     let url = baseURL+toolListString 

     guard let myURL = URL(string: url) else { 
      print("URL not defined properly") 
      return nil 
     } 
     guard let parser = XMLParser(contentsOf: myURL as URL) else { 
      print("Cannot Read Data") 
      return nil 
     } 

     parser.delegate = ToolXMLParserDelegate(toolList: &toolList) 

     if !parser.parse() { //HERE I GET THE ERROR 
      print("Data Errors Exist:") 
      let error = parser.parserError! 
      print("Error Description:\(error.localizedDescription)") 
      //print("Error reason:\(error.localizedFailureReason)") 
      print("Line number: \(parser.lineNumber)") 
     } 

     return toolList 
    } 
} 

ToolXMLParserDelegate.swift：

import Foundation 

class ToolXMLParserDelegate : NSObject, XMLParserDelegate { 

    var tools: [Tool] = [] 
    var eName: String = String() 
    var toolId = String() 
    var toolName = String() 

    init(toolList : inout [Tool]) { 
     self.tools = toolList 
    } 


    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) { 
     eName = elementName 
     if elementName == "row" { 
      toolId = String() 
      toolName = String() 
     } 
    } 


    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) { 
     if elementName == "row" { 

      let tool = Tool() 
      tool.id = Int(toolId)! 
      tool.name = toolName 
      tools.append(tool) 
     } 
    } 


    func parser(_ parser: XMLParser, foundCharacters string: String) { 
     let data = string.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines) 

     if (!data.isEmpty) { 
      if eName == "id" { 
       toolId += data 
      } else if eName == "name" { 
       toolName += data 
      } 
     } 
    } 
} 

Tool.swift：

import UIKit 

class Tool: NSObject { 

    var id: Int = Int() 
    var name: String = String() 

    override init() {} 

    init(id: Int, name: String) { 
     self.id = id 
     self.name = name 
    } 

    init(name: String) { 
     self.name = name 
    } 
} 

ToolTableViewController.swift：（使用XMLHelper.getToolList（））

import UIKit 

class ToolTableViewController: UITableViewController, XMLParserDelegate { 

    var tools: [Tool] = [] 
    var eName: String = String() 
    var toolId = String() 
    var toolName = String() 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     tableView.tableFooterView = UIView() // to remove empty cells in the list 
    } 

    override func viewWillAppear(_ animated: Bool) { 
     tools = XMLHelper.getToolList()! 

     // this code piece is working, but i want to outsource it, so i can use it again 
     /* 
     let url = "{myUrl}" // not public for security reason 
     let myURL = URL(string: url) 
     let parser = XMLParser(contentsOf: myURL!)! 
     parser.delegate = self as XMLParserDelegate 
     parser.parse() 
     */ 

     tableView.reloadData()*/ 

     print("view did refresh") 
    } 


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

    // MARK: - Table view data source 

    override func numberOfSections(in tableView: UITableView) -> Int { 
     return 1 
    } 

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { 
     return tools.count 
    } 


    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { 
     //let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath) 

    let cellIdentifier = "ToolTableViewCell" // simple TableViewCell with a label 

    guard let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as? ToolTableViewCell else { 
     fatalError("The dequeued cell is not an instance of ToolTableViewCell.") 
    } 

    let tool = tools[indexPath.row] 

    cell.labelName.text = String(tool.id)+" "+tool.name 

    return cell 
} 

// MARK: XMLParserDelegate (this code here is only used when the code above is uncommented, it is the same as the code in ToolXMLParserDelegate) 

    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) { 
     eName = elementName 
     if elementName == "row" { 
      toolId = String() 
      toolName = String() 
     } 
    } 

    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) { 
     if elementName == "row" { 

      let tool = Tool() 
      tool.id = Int(toolId)! 
      tool.name = toolName 

      tools.append(tool) 
     } 
    } 

    func parser(_ parser: XMLParser, foundCharacters string: String) { 
     let data = string.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines) 

     if (!data.isEmpty) { 
      if eName == "id" { 
       toolId += data 
      } else if eName == "name" { 
       toolName += data 
      } 
     } 
    } 
} 

Answer 1

我它現在工作，它看起來像我搞砸了參考秒。

這裏是我變了：

ToolXMLParserDelegate

init(toolList : [Tool]) { //removed inout 
    self.tools = toolList 
} 

XMLHelper

class func getToolList() -> [Tool]? { 
    // not needed anymore 
    //var toolList: [Tool] = [] 

    let baseURL = "https://henkel.simonus.de/approval/xml/" 
    let toolListString = "getToolList.php" 

    let url = baseURL+toolListString 

    guard let myURL = URL(string: url) else { 
     print("URL not defined properly") 
     return nil 
    } 
    guard let parser = XMLParser(contentsOf: myURL as URL) else { 
     print("Cannot Read Data") 
     return nil 
    } 

    // CHANGES 
    let myDelegate = ToolXMLParserDelegate(toolList: []) // pass an empty array 
    parser.delegate = myDelegate 

    if !parser.parse() { 
     print("Data Errors Exist:") 
     let error = parser.parserError! 
     print("Error Description:\(error.localizedDescription)") 
     //print("Error reason:\(error.localizedFailureReason)") 
     print("Line number: \(parser.lineNumber)") 
    } 

    // return the list of the delegate instead of the xmlhelpers toolList 
    return myDelegate.tools 
}