let xml = "<?xml version=\"1.0\" encoding=\"UTF-8\" ?><foo>Hello World!</foo>"
if let parser = XMLPullParser(string: xml) {
    do {
        parsing: while true {
            switch try parser.next() {
            case .startDocument:
                print("start document")
            case .startElement(let name, _, _):
                print("start element: \(name)")
            case .characters(let text):
                print("text: \(text)")
            case .endElement(let name, _):
                print("end element: \(name)")
            case .endDocument:
                print("end document")
                break parsing
            }
        }
    } catch let error {
        print("error: \(error)")
    }
}

let event = try parser.next()
switch event {
case .startElement("foo", _, _):
    // handle start of <foo>
    print("foo: \(event)")
case .startElement("bar", _, _):
    // handle start of <bar>
    print("bar: \(event)")
case .startElement("baz", "http://example.com/ns/1.0"?, let element):
    // handle start of <baz>, whose namespace URI is http://example.com/ns/1.0
    // note: you must set parser.shouldProcessNamespaces true to handle namespaces
  
    // you can get attributes from XmlElement object
    print(element.attributes["xyz"])
case .startElement(_, _, _):
    // handle start of other elements
    print("other: \(event)")
default:
    break
}