Question

Is anybody famaliar with how to use TTXMLParser. I can’t find any documentation or sample code on it.

Is it SAX or DOM?

Does it support Xpath?

Can I extract CDATA from elements?

I have an application that already uses several Three20 modules it would be a shame to have to use another parser.

Answer 1

The main documentation I’ve found for TTXMLParser is in the header file. The comment there gives an overview of what TTXMLParser does.

TTXMLParser shouldn’t really be thought of as an XML parser in the way you are thinking of it — in this sense, questions such as “is it SAX or DOM” and “does it support XPath” aren’t directly applicable. Instead, think of TTXMLParser as a convenience class to take XML and turn it into a tree of Objective-C objects. For example, this XML node:

<myNode attr1="value1" attr2="value2" />

would be turned into an Objective-C NSDictionary node which mapped the key “attr1” to the value “value1” and the key “attr2” to the key “value2”.

TTXMLParser internally uses NSXMLParser (which is basically SAX) to build up its tree, but you, as the user of TTXMLParser, don’t have to do any SAX-like stuff.

So, no, you will not end up with an XML document on which you can perform XPath queries. Instead, you will end up with an Objective-C tree of objects. If that’s what you want, great; if you want a traditional XML parser with XPath, I’m currently working on a project that uses both Three20 and TouchXML. TouchXML supports XPath.

I agree it’s hard to find sample code for TTXMLParser. Three20’s TTTwitter sample used to use TTXMLParser (well actually, TTURLXMLResponse, which in turn uses TTURLParser), but at some point it was changed to use TTURLJSONResponse instead, which is a shame, because this was their only XML sample.

You can still see the old XML-based sample code here. Specifically, look at the -[requestDidFinishLoad:] function near the bottom of the file, for an example of some code that takes a TTURLXMLResponse, queries its rootObject member, and then walks down the resulting tree of objects.