Wie NSXMLParser auf Elemente nach einem bestimmten Element zu beschränken

Question

Wie dieser XML-Code unten gebildet wird, erhält mein Code sowohl die n13 Zeitperioden als auch die n7 Zeiträume, ist es möglich, meine Ergebnisse auf nur die n13 Daten zu beschränken irgendwie?

<time-layout time-coordinate="local" summarization="12hourly"> 
<layout-key>k-p12h-n13-1</layout-key> 
<start-valid-time period-name="This Afternoon">2016-06-30T12:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Tonight">2016-06-30T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Friday">2016-07-01T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Friday Night">2016-07-01T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Saturday">2016-07-02T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Saturday Night">2016-07-02T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Sunday">2016-07-03T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Sunday Night">2016-07-03T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Independence Day">2016-07-04T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Monday Night">2016-07-04T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Tuesday">2016-07-05T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Tuesday Night">2016-07-05T18:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Wednesday">2016-07-06T06:00:00-04:00</start-valid-time> 
</time-layout> 
<time-layout time-coordinate="local" summarization="12hourly"> 
<layout-key>k-p24h-n7-1</layout-key> 
<start-valid-time period-name="This Afternoon">2016-06-30T12:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Friday">2016-07-01T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Saturday">2016-07-02T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Sunday">2016-07-03T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Independence Day">2016-07-04T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Tuesday">2016-07-05T06:00:00-04:00</start-valid-time> 
<start-valid-time period-name="Wednesday">2016-07-06T06:00:00-04:00</start-valid-time> 
</time-layout> 

mein DidStartElement Code:

if weAreInsideAnItem == true { 

      if (elementName as NSString).isEqualToString("start-valid-time") { 

       if let periodAsNSString: NSString = attributeDict["period-name"] { 
        guard let periodAsString: String = periodAsNSString as String else {return} 
        tempForecastTimes.append(periodAsString) 

       } 
      } 
     } 

Answer 1

In Verarbeitungselement layout-key genannt, sehen, wenn sein Wert auf etwas gleich war, z.B. k-p12h-n13-1, und wenn dies der Fall ist, setze eine Zustandsvariable, z. isInN13. Bei der Verarbeitung von start-valid-time können Sie dann diese Statusvariable berücksichtigen. Zum Beispiel:

var value: String? 
var isInN13 = false 

func parser(parser: NSXMLParser, didStartElement elementName: String, namespaceURI: String?, qualifiedName qName: String?, attributes attributeDict: [String : String]) { 
    if elementName == "layout-key" { 
     value = "" 
    } 

    if elementName == "start-valid-time" && isInN13 { 
     value = "" 
    } 
} 

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

func parser(parser: NSXMLParser, didEndElement elementName: String, namespaceURI: String?, qualifiedName qName: String?) { 
    if elementName == "layout-key" { 
     isInN13 = value == "k-p12h-n13-1" 
    } 

    if elementName == "start-valid-time" && isInN13 { 
     print(value) 
    } 

    value = nil 
}