Can SwiftSoup work with XML documents as well as HTML?

SwiftSoup is a pure Swift library that is primarily designed for parsing and manipulating HTML. It provides a convenient API for extracting data, traversing the DOM (Document Object Model), and manipulating HTML elements and attributes. SwiftSoup is inspired by the popular Java library Jsoup, which is widely used for the same purposes.

While SwiftSoup's main focus is on HTML content, XML and HTML share similarities in their structure, as they are both markup languages that use tags to define elements within a document. Because of these similarities, SwiftSoup can be used for some basic XML parsing tasks. However, it is important to note that SwiftSoup is not a full-fledged XML parser, and it may not support all XML-specific features such as namespaces, processing instructions, and some other XML standards.

SwiftSoup tends to handle XML documents that closely resemble HTML well, but for more complex XML parsing requirements, it would be more appropriate to use a dedicated XML parser. In the Swift ecosystem, libraries like XMLParser (part of Foundation) or third-party libraries are better suited for comprehensive XML handling.

Below is an example of how you might use SwiftSoup to parse a simple XML document:

import SwiftSoup

let xml = """
<catalog>
   <book id="bk101">
      <author>Gambardella, Matthew</author>
      <title>XML Developer's Guide</title>
      <genre>Computer</genre>
      <price>44.95</price>
   </book>
   <book id="bk102">
      <author>Ralls, Kim</author>
      <title>Midnight Rain</title>
      <genre>Fantasy</genre>
      <price>5.95</price>
   </book>
</catalog>
"""

do {
    let xmlDoc = try SwiftSoup.parse(xml, "", Parser.xmlParser())
    for book in try xmlDoc.select("book") {
        let id = try book.attr("id")
        let title = try book.select("title").text()
        let author = try book.select("author").text()
        let price = try book.select("price").text()

        print("Book ID: \(id)")
        print("Title: \(title)")
        print("Author: \(author)")
        print("Price: \(price)\n")
    }
} catch {
    print("Error parsing XML: \(error)")
}

This code snippet shows how you can use SwiftSoup to parse a simple XML file, extract data from it, and print out the details of each <book> element. The key here is to use Parser.xmlParser() to instruct SwiftSoup to parse the document as XML.

However, for more advanced XML features, you should consider using a specialized XML parser designed specifically for Swift. Here is an example using the XMLParser:

import Foundation

let xmlData = xml.data(using: .utf8)!
let parser = XMLParser(data: xmlData)
let delegate = MyXMLParserDelegate() // This would be a custom class conforming to XMLParserDelegate protocol
parser.delegate = delegate
parser.parse()

In this example, you would need to implement the XMLParserDelegate protocol methods in your MyXMLParserDelegate class to handle the start and end of elements, character data, and potential errors during parsing.

In conclusion, while SwiftSoup can be used for basic XML parsing, especially for XML that closely resembles HTML, it is recommended to use dedicated XML parsing libraries for full XML support in Swift.