Swift parsing attribute name for given elementName

问题:

Here is a part of my URL

<cities>
  <country name="Абхазия">
    <city id="37188" region="27028" head="" type="3" country="Абхазия" part="" resort="" climate="">Новый Афон</city>
    <city id="37178" region="10282" head="" type="3" country="Абхазия" part="" resort="" climate="">Пицунда</city>
    <city id="37187" region="37187" head="" type="3" country="Абхазия" part="" resort="" climate="">Гудаута</city>
    <city id="37172" region="10280" head="" type="3" country="Абхазия" part="" resort="" climate="">Гагра</city>
    <city id="37189" region="10281" head="0" type="3" country="Абхазия" part="" resort="0" climate="">Сухум</city>
  </country>

User types the name of the city, for example: "Пицунда" and I want to get its id. For "Пицунда" id is "10282".

Below I've posted my not-working code.

var parser: NSXMLParser!
var city: String = String()
var ifDirOK = false
var ifCityNameOK = false


override func viewDidLoad() {
    super.viewDidLoad()

    let url: NSURL = NSURL(string: "https://pogoda.yandex.ru/static/cities.xml")!

    parser = NSXMLParser(contentsOfURL: url)
    parser.delegate = self
    parser.parse()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}



func parser(parser: NSXMLParser!, didStartElement elementName: String!, namespaceURI: String!, qualifiedName qName: String!, attributes attributeDict: [NSObject : AnyObject]!) {
    //let cityID = attributeDict ["id"] as? NSString
    if (elementName == "city"){
        ifDirOK = true
    }
}

func parser(parser: NSXMLParser!, foundCharacters string: String!) {
    var data = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
    if (data == city){
        ifCityNameOK = true
    }
}

func parser(parser: NSXMLParser!, foundAttributeDeclarationWithName attributeName: String!, forElement elementName: String!, type: String!, defaultValue: String!) {
    if (ifDirOK && ifCityNameOK){
        println("\(attributeName)")
    }
}

func parser(parser: NSXMLParser!, didEndElement elementName: String!, namespaceURI: String!, qualifiedName qName: String!) {
}

After all, I want to pass id to another URL file (export.yandex.ru/weather-ng/forecasts/{id of the city}.xml) and parse it. Do I need to create another Swift class and somehow connect it with first one?

回答1:

Building a dictionary of [city:id] can be a solution for you. I have implemented a simple solution based on the article about lifecycle of NSXMLParser at http://www.codeproject.com/Articles/248883/Objective-C-Fundamentals-NSXMLParser .

Following method is called when when an element is starting. You can retrieve city id attribute and save it in an instance level variable so that you can use it in the next method.

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [NSObject : AnyObject]) 

And then, Following method is called when the parser see anything between starting and ending.

func parser(parser: NSXMLParser!, foundCharacters string: String!) 

So, you can get the city name from here. Now we have city id and city name to add a new item into the [city:id] dictionary.

Once you build the dictionary, searching would be very simple.

here is my working test code.

class ViewController: UIViewController ,NSXMLParserDelegate{
    var parser: NSXMLParser!
    var city: String = String()
    var ifDirOK = false
    var ifCityNameOK = false
     var element : String?
    var value: String=String()
    var dic = Dictionary<String,String>()
    var currentCityId:String?
    @IBOutlet weak var result: UILabel!

    @IBOutlet weak var search: UITextField! //search text

    @IBAction func ActionGoGetIt(sender: AnyObject) {

        self.result.text=dic[self.search.text]
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        let url: NSURL = NSURL(string: "https://pogoda.yandex.ru/static/cities.xml")!

        parser = NSXMLParser(contentsOfURL: url)
        parser.delegate = self
        parser.parse()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }



    func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [NSObject : AnyObject]) {
        element = elementName

        if (element == "city"){
            ifDirOK = true
            let cityID = attributeDict ["id"] as? NSString
            self.currentCityId = cityID  as? String

        }
    }

    func parser(parser: NSXMLParser!, foundCharacters string: String!) {
        var data = string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())

        if (!data.isEmpty){
             if (element == "city"){
                    dic[data] = self.currentCityId as String?
            }

        }
    }

    func parser(parser: NSXMLParser, foundAttributeDeclarationWithName attributeName: String, forElement elementName: String, type: String?, defaultValue: String?) {
        if (ifDirOK && ifCityNameOK){
            println("\(attributeName)")
        }
    }

    func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) {

    }

}