将字符串中包含数字的XML响应转换为Int Swift

class XMLResponseParser: NSObject, XMLParserDelegate {
    var isParsingNumber = false
    var parsedNumber: Int?
    
    func parseXMLResponse(response: String) -> Int? {
        let data = response.data(using: .utf8)
        let parser = XMLParser(data: data!)
        parser.delegate = self
        parser.parse()
        
        return parsedNumber
    }
    
    // 处理开始标签
    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String] = [:]) {
        if elementName == "number" {
            isParsingNumber = true
        }
    }
    
    // 处理结束标签
    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
        if elementName == "number" {
            isParsingNumber = false
        }
    }
    
    // 处理标签内容
    func parser(_ parser: XMLParser, foundCharacters string: String) {
        if isParsingNumber {
            parsedNumber = Int(string)
        }
    }
}

let xmlResponse = "<response><number>42</number></response>"
let parser = XMLResponseParser()
let number = parser.parseXMLResponse(response: xmlResponse)

print(number) // 输出：Optional(42)