Although JSON is more commonly used, there are still many XML-based network services. Fortunately XML parsing has existed in iOS since version 5 in the
NSXMLParser class and is simple to access from Swift. For example, some data feeds (such as blog posts) use XML documents, such as Atom or RSS.
NSXMLParser is a stream-oriented parser; that is, it reports individual elements as they are seen. The parser calls the
delegate to notify when elements are seen and have finished. When an element is seen, the parser also includes any attributes that were present; and for text nodes, the string content. Parsing an XML file involves some state management in the parser. The example used in this section will be to parse an Atom (news feed) file, ...