我是解析方面的新手，找不到任何不过时且不会提出更多问题的教程。我有一个要解析的简单 xml 文件 url。 xml 非常简单:

<xml>
    <record>
        <EmpName>A Employee</EmpName>
        <EmpPhone>111-222-3333</EmpPhone>
        <EmpEmail>a@employee.com</EmpEmail>
        <EmpAddress>12345 Fake Street</EmpAddress>
        <EmpAddress1>MyTown, Mystate ZIP</EmpAddress1>
    </record>
</xml>

只是想将其保存为 NSDictionary(标签作为键，数据作为值)。到目前为止，我所能成功完成的就是在控制台中打印 xml 字符串:

let url = NSURL(string: "http://www.urlexample.com/file.xml")

let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
        println(NSString(data: data, encoding: NSUTF8StringEncoding))
}
print(task)
task.resume()

我浏览过我发现的所有在线教程，但这些教程要么已经过时，要么过于复杂。感谢您的帮助。

最佳答案

过程很简单:

1. 创建 XMLParser 对象，将数据传递给它。
2. 为该解析器指定委托(delegate)。
3. 开始解析。

所以，在 Swift 3/4 中，它看起来像:

let task = URLSession.shared.dataTask(with: url) { data, response, error in
    guard let data = data, error == nil else {
        print(error ?? "Unknown error")
        return
    }

    let parser = XMLParser(data: data)
    parser.delegate = self
    if parser.parse() {
        print(self.results ?? "No results")
    }
}
task.resume()

问题是如何实现 XMLParserDelegate 方法。三个关键方法是 didStartElement(准备接收字符的地方)、foundCharacters(处理解析的实际值的地方)和 didEndElement(保存结果的位置)。

您询问了如何解析单个记录(即单个字典)，但我将向您展示一个更通用的模式来解析一系列记录，这在 XML 中更为常见。如果您不需要值数组(或只获取第一个值)，您显然可以看到如何简化它。

// a few constants that identify what element names we're looking for inside the XML

// a few constants that identify what element names we're looking for inside the XML

let recordKey = "record"
let dictionaryKeys = Set<String>(["EmpName", "EmpPhone", "EmpEmail", "EmpAddress", "EmpAddress1"])

// a few variables to hold the results as we parse the XML

var results: [[String: String]]?         // the whole array of dictionaries
var currentDictionary: [String: String]? // the current dictionary
var currentValue: String?                // the current value for one of the keys in the dictionary

和

extension ViewController: XMLParserDelegate {

    // initialize results structure

    func parserDidStartDocument(_ parser: XMLParser) {
        results = []
    }

    // start element
    //
    // - If we're starting a "record" create the dictionary that will hold the results
    // - If we're starting one of our dictionary keys, initialize `currentValue` (otherwise leave `nil`)

    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 = ""
        }
    }

    // found characters
    //
    // - If this is an element we care about, append those characters.
    // - If `currentValue` still `nil`, then do nothing.

    func parser(_ parser: XMLParser, foundCharacters string: String) {
        currentValue? += string
    }

    // end element
    //
    // - If we're at the end of the whole dictionary, then save that dictionary in our array
    // - If we're at the end of an element that belongs in the dictionary, then save that value in the dictionary

    func parser(_ parser: XMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {
        if elementName == recordKey {
            results!.append(currentDictionary!)
            currentDictionary = nil
        } else if dictionaryKeys.contains(elementName) {
            currentDictionary![elementName] = currentValue
            currentValue = nil
        }
    }

    // Just in case, if there's an error, report it. (We don't want to fly blind here.)

    func parser(_ parser: XMLParser, parseErrorOccurred parseError: Error) {
        print(parseError)

        currentValue = nil
        currentDictionary = nil
        results = nil
    }

}

有关 Swift 2 版本，请参阅 previous revision of this answer .

关于xml - 在 Swift 中从 URL 解析 XML，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/31083348/