Xmlparser.Sharedparser.Decode() in Swift3

Parsing XML from URL in Swift

The process is simple:

1. Create XMLParser object, passing it the data.
2. Specify the delegate for that parser.
3. Initiate the parsing.

So, in Swift 3/4, that looks like:

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()

The question is how do you implement the XMLParserDelegate methods. The three critical methods are didStartElement (where you prepare to receive characters), foundCharacters (where you handle the actual values parsed), and didEndElement (where you save you results).

You asked how to parse a single record (i.e. a single dictionary), but I'll show you a more general pattern for parsing a series of them, which is a far more common situation with XML. You can obviously see how to simplify this if you didn't need an array of values (or just grab the first one).

// 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

And

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
    }

}

For Swift 2 rendition, see previous revision of this answer.

xml parsing in iOS swift

Here's some parsing code I wrote in Swift 3 based off of a Google News RSS reader I previously wrote in Swift 2.0. I have this code modified to handle a list of PrintLetterBarcodeData elements as well as a single one:

class BarcodeData {
    var uid: String
    var name: String
    var gender: String
    var yob: String
    var co: String
    var house: String
    var street: String
    var lm: String
    var vtc: String
    var po: String
    var dist: String
    var subdist: String
    var state: String
    var pc: String
    var dob: String

    init?(dictionary: [String : String]) {
        guard let uid = dictionary["uid"],
            let name = dictionary["name"],
            let gender = dictionary["gender"],
            let yob = dictionary["yob"],
            let co = dictionary["co"],
            let house = dictionary["house"],
            let street = dictionary["street"],
            let lm = dictionary["lm"],
            let vtc = dictionary["vtc"],
            let po = dictionary["po"],
            let dist = dictionary["dist"],
            let subdist = dictionary["subdist"],
            let state = dictionary["state"],
            let pc = dictionary["pc"],
            let dob = dictionary["dob"] else {
            return nil
        }

        self.uid = uid
        self.name = name
        self.gender = gender
        self.yob = yob
        self.co = co
        self.house = house
        self.street = street
        self.lm = lm
        self.vtc = vtc
        self.po = po
        self.dist = dist
        self.subdist = subdist
        self.state = state
        self.pc = pc
        self.dob = dob

    }
}

class MyParser: NSObject {
    var parser: XMLParser

    var barcodes = [BarcodeData]()

    init(xml: String) {
        parser = XMLParser(data: xml.data(using: String.Encoding.utf8)!)
        super.init()
        parser.delegate = self
    }

    func parseXML() -> [BarcodeData] {
        parser.parse()
        return barcodes
    }

}

extension MyParser: XMLParserDelegate {

    func parser(_ parser: XMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) {

        if elementName == "PrintLetterBarcodeData" {

            if let barcode = BarcodeData(dictionary: attributeDict) {
                barcodes.append(barcode)
            }
        }
    }
}

Usage:

let xmlString = "<?xml version=\"1.0\" encoding=\"UTF-8\"?><PrintLetterBarcodeData uid=\"685860050795\" name=\"Sangeetha D\" gender=\"F\" yob=\"1989\" co=\"W/O: Dhanansekaran\" house=\"632\" street=\"saradhambal nagar\" lm=\"agaramel\" vtc=\"Nazarathpettai\" po=\"Nazarethpettai\" dist=\"Tiruvallur\" subdist=\"Poonamallee\" state=\"Tamil Nadu\" pc=\"600123\" dob=\"03/06/1989\"/>"

let parser = MyParser(xml: xmlString)
let barcodes = parser.parseXML() // array of barcodes
barcodes.first // your barcode

Handling XML data with Alamofire in Swift

If I did not misunderstand your description, I think you would like to get the XML data and parse it, right? Regarding to this, you may handle with wrong variables in the response callback. You should println(data) to check the XML document.

For parsing XML data, you could consider SWXMLHash. The Alamofire request could look like:

Alamofire.request(.GET, "http://my-web-service-domain.com", parameters: nil)
         .response { (request, response, data, error) in
            println(data) // if you want to check XML data in debug window.
            var xml = SWXMLHash.parse(data!)
            println(xml["UserDTO"]["FilmID"].element?.text) // output the FilmID element.
         }

Further information about XML management, please check SWXMLHash.

Something like Callback in Swift

Delegates are the other way of doing it, closures also preferred though

---

Related Topics