构建[city：id]字典可以为您提供解决方案。我基于http://www.codeproject.com/Articles/248883/Objective-
C-Fundamentals-
NSXMLParser上有关NSXMLParser生命周期的文章，实现了一个简单的解决方案。

当元素开始时，调用以下方法。您可以检索城市ID属性并将其保存在实例级别的变量中，以便可以在下一个方法中使用它。

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

然后，当解析器看到开始和结束之间的任何内容时，将调用Following方法。

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

因此，您可以从此处获取城市名称。现在我们有了城市ID和城市名称，可以在[city：id]字典中添加新项目。

建立字典后，搜索将非常简单。

这是我的工作测试代码。

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?) {

    }

}