XMLParser returning "NULL Value"

Question

The service am trying to parse is here: http://maps.googleapis.com/maps/api/geocode/xml?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA&sensor=false

I am trying to parse a simple xml. The structure of the xml looks something like this:

<GeocodeResponse>
 <status>OK</status>
 <result>
  <type>street_address</type>
............
............

My parsing code is:

-(void)parserDidStartDocument:(NSXMLParser *)parser{
}
-(void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:    (NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    NSLog(@"Element Name is =%@, \nNamespaceURI is =%@, \nQualifiedName is =%@, \n, Attributes     Dictionary is = %@",elementName,namespaceURI,qName,attributeDict);
     currentEltValue = elementName;
    if([elementName isEqualToString:@"status"]){
        parsedata = [[NSString alloc ]init];
        NSLog(@"Initializing the variable here");
    }

}
-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{

    if([currentEltValue isEqualToString:@"status"]){

        NSLog(@"Inside if loop");
        parsedata = string;
        NSLog(@"Found Characters value is = %@",parsedata);

    }
    else parsedata = NULL;
}
-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString      *)namespaceURI qualifiedName:(NSString *)qName
{
    if([elementName isEqualToString:@"status"]){
        NSLog(@"PARSED DATA: = %@",parsedata);
    }

}
- (void)parserDidEndDocument:(NSXMLParser *)parser {
    NSLog(@"Did end document \t parseData Valus is =%@",parsedata);

 }

When i run the program, in my console i am getting:

2012-08-01 13:21:10.721 XML_Parsing[5624:207] Element Name is =status, 
NamespaceURI is =(null), 
QualifiedName is =(null), 
, Attributes Dictionary is = {
}
2012-08-01 13:21:10.722 XML_Parsing[5624:207] Initializing the variable here
2012-08-01 13:21:10.722 XML_Parsing[5624:207] Inside if loop
2012-08-01 13:21:10.723 XML_Parsing[5624:207] Found Characters value is = OK
2012-08-01 13:21:10.723 XML_Parsing[5624:207] PARSED DATA: = OK
2012-08-01 13:21:10.724 XML_Parsing[5624:207] Inside if loop
2012-08-01 13:21:10.724 XML_Parsing[5624:207] Found Characters value is = 
2012-08-01 13:21:10.803 XML_Parsing[5624:207] Did end document   parseData Valus is =(null)

I have no clue as to why the if condition is running twice?

UPDATE *Solution* This solved my problem:

1] In the DidEndElement: declare currentEltValue = @"".

2] Access all instances of parsedata as self.parsedata.

Answer 1

According to the docs,

The parser object may send the delegate several parser:foundCharacters: messages to report the characters of an element. Because string may be only part of the total character content for the current element, you should append it to the current accumulation of characters until the element changes.

So that would explain why the if condition is executed multiple times. Perhaps the second string is just empty. Try printing the length of each string. Maybe its getting called for another status element.

As to why parseData is NULL, its happening in the else part.

else parsedata = NULL;

Bear in mind that parser:foundCharacters: gets called for other elements also. So when the parser finishes, it would have encountered those elements and parseData would have got assigned to null.

Answer 2

Replace your delegate method as follows, You have to set the currentEltValue to empty string when the tag is ended.

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString      *)namespaceURI qualifiedName:(NSString *)qName
{
    if([elementName isEqualToString:@"status"]){
        NSLog(@"PARSED DATA: = %@",parsedata);
        currentEltValue=@"";
    }

}

-(void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{

    if([currentEltValue isEqualToString:@"status"]){

        NSLog(@"Inside if loop");
        parsedata = string;
        NSLog(@"Found Characters value is = %@",parsedata);

    }

}