XPath how to select the first element without loading the whole xml?

Question

Hello everybody,

Im using libxml2 on the iPhone with the nice Method: PerformXMLXPathQuery from Cocoa with Love. The problem is how to find out witch xml got sent without first parsing the whole document... I tried to use the @"/" query to retrieve the first element as written on the introduction of Cocoa with Love but unfortunately, the PerformXMLXPathQuery crashes cause of this query!

When I use the @"/*" command the whole tree gets parsed, which is very inefficient in terms of time and memory consumption..

Any Ideas how this works?

Thanks Markus

Answer 1

I'm not sure how tight your performance requirements are, but using a SAX parser, such as NSXMLParser, would enable you to quit parsing after you processed the element you're looking for. See the

- (void)abortParsing

method on the parser, and

– parser:didStartElement:namespaceURI:qualifiedName:attributes:
– parser:didEndElement:namespaceURI:qualifiedName:

on the NSXMLParserDelegate protocol.