爲什麼我的XML解析器不斷通過Swift中的標記迭代？

我試圖解析XML格式的天氣數據，但我的解析器似乎遍歷所有的標籤，而不是我指定的標籤。所以，我有我的didStartElement功能：爲什麼我的XML解析器不斷通過Swift中的標記迭代？

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) 
{ 
    if(elementName == "cap:event") { 
     capEventFound = true 
    } 
}

和我didEndElement功能：

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [NSObject : AnyObject]) 
{ 
    if(elementName == "cap:event") { 
     capEventFound = false 
    } 
}

我的解析器功能：解析

func parser(parser: NSXMLParser, foundCharacters string: String) 
{ 
    if(capEventFound) 
    { 
     newsStories.append(string) 
     print(newsStories) 
    } 
    else 
    { 
     print("No cap:event found") 
    } 
}

其他相關功能：

override func viewDidLoad() { 
    super.viewDidLoad() 
    self.pvState.delegate = self 
    self.pvState.dataSource = self 
    stateCode = ["AL", "AK", "AZ", "AR", "CA", "CO", "CT", "DE", "FL", "GA", "HI", "ID", "IL", "IN", "IA", "KS", "KY", "LA", "ME", "MD", "MA", "MI", "MN", "MS", "MO", "MT", "NE", "NV", "NH", "NJ", "NM", "NY", "NC", "ND", "OH", "OK", "OR", "PA", "RI", "SC", "SD", "TN", "TX", "UT", "VT", "VA", "WA", "WV", "WI", "WY"] 
} 

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int 
{ 
    return 1 
} 

func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
{ 
    return stateCode.count 
} 

func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
{ 
    return stateCode[row] 
} 

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
{ 
    selectedState = stateCode[pickerView.selectedRowInComponent(0)] 
    url = "http://alerts.weather.gov/cap/\(selectedState).php?x=0" 
    urlStr = url.stringByAddingPercentEncodingWithAllowedCharacters(NSCharacterSet.URLQueryAllowedCharacterSet())! 
    searchURL = NSURL(string: urlStr as String)! 
    xmlParser = NSXMLParser(contentsOfURL: searchURL)! 
    xmlParser.delegate = self 
    xmlParser.parse() 
}

我的輸出，例如當我選擇科羅拉多在這裏：http://pastebin.com/v3ULvQ0G

爲什麼它這樣做，我怎麼才能得到它只發布相關的帽：事件？

來源

2016-10-05 CsCody

它繼續遍歷標籤，因爲它永遠不會調用didEndElement。這是因爲你的didEndElement聲明不正確，因此沒有像你期望的那樣被調用。此聲明：

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [NSObject : AnyObject]) { ... }

應該是：

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

無關，但你的過程，在foundCharacters附加價值是有點危險，因爲它在理論上是可能的，它需要多個調用foundCharacters返回完整的事件名稱。您通常只應追加foundCharacters中的字符，並在didEndElement中更新您的模型結構。例如，我可能會建議：

var parsedString: String? 

// element starts 

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) { 
    if elementName == "cap:event" { 
     parsedString = String() 
    } 
} 

// characters found 
// 
// this may be called more than once 

func parser(parser: NSXMLParser, foundCharacters string: String) { 
    parsedString? += string 
} 

// element ended 
// 
// but, by the time we get here, we have the full parsed string 

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) { 
    if elementName == "cap:event" { 
     newsStories.append(parsedString!) 
     parsedString = nil 
    } 
}

來源

2016-10-05 23:05:02 Rob

爲什麼我的XML解析器不斷通過Swift中的標記迭代？

回答

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