Comments on: Cocoa Tutorial: libxml and xmlreader

By: karlmeier

karlmeier — Wed, 22 Sep 2010 06:01:22 +0000

Yeah, I have. Hasn't helped me too much though. It doesn't use native libxml to extract the attributes and uses DOM. I'm trying to build a simple SAX parser that returns a neat dictionary that I can use. Furthermore, the TouchXML project seems to have vanished from Google code. I managed to find the code on the web, but didn't have much luck with the documentation for it ;-)

Seems like I have to do a little digging myself then... oh well. Thanks for the tip though.

By: Marcus Zarra

Marcus Zarra — Mon, 20 Sep 2010 20:48:23 +0000

Have you looked at TouchXML at all? It is also based on libxml2 and may shed some light on the issue for you.

By: karlmeier

karlmeier — Mon, 20 Sep 2010 20:29:51 +0000

Thanks a lot for this post. it turns out to be way faster than my implementation with NSXMLParser. However I haven't managed to extend it in a way that the attributes of tags are parsed into the dictionary.

My testing for "case XML_READER_TYPE_ATTRIBUTE:" is never being called and I have issues understanding the libxml2 documentation. As far as I can tell my test should work.

Turns out that nobody has implemented this in objective-c apparently, as far as Google knows anyway. Could you give me a hint on what I'm missing??

Oh and btw, I found that you probably should replace the return in "if (!currentPerson) return;" with a break.

Thanks in advance

By: maurj

maurj — Wed, 03 Sep 2008 13:11:33 +0000

Just recently, I’ve been working “without NSXMLDocument”, although I didn’t realise this till about 2 days of development had passed. Grr. Like yourself, I started looking for an alternative, and ended up working with libxml directly (with great success, I should add). I’m going for a more direct “xmlReadMemory” approach than described here, but the principle is the same. Wish I’d found your article a few days ago.

I thought I should let you know that the same approach described here can be used to work with libxslt (for XSLT transformations) and libtidy (for HTML tidying – e.g to convert HTML into XHTML). As with libxml, you might need to find your own copies of the headers in each case, as they aren’t included by default. And if the local copy of your slimmed-down Mac OS X installation doesn’t have the libxslt and libtidy dylibs to hand, then you might need to borrow the copies from a non-slimmed-down version too.

By: Marcus Zarra

Marcus Zarra — Mon, 25 Aug 2008 00:08:06 +0000

Where do you see irritative? Perhaps you meant to type iterative?

While XML itself is not iterative, the method that this article uses for reading it is.

By: klacoste

klacoste — Sun, 24 Aug 2008 10:44:48 +0000

In the 4th paragraph, when talking about the XML data file, there's a typo in there. I'm pretty sure the XML is not "irritative". Then again, if that's what you really meant, I think I'd understand.

PS: Cheers for the blog. I enjoy reading it. Keep the posts coming!

By: Matthieu Cormier

Matthieu Cormier — Tue, 19 Aug 2008 14:17:07 +0000

"slimmed down version of OS X."

OS X is perfect why would you need to slim it down? ;)

By: MattGallagher

MattGallagher — Tue, 19 Aug 2008 05:52:21 +0000

If you're only missing the NSXMLDocument class (in your ahem hypothetical case), it should be possible to use the NSXMLParser class instead of raw libxml2 for Event-Driven XML handling. It is similarly fast and lightweight.

Of course, NSXMLParser is strict, so will fail on malformed XML.

I personally use neither, instead falling back to the libxml parser instead of reader (xmlDocPtr) since I like to use XPath queries (xmlXPathEvalExpression) tp extract my nodes. I'm so heavyweight.

By: wadetregaskis

wadetregaskis — Tue, 19 Aug 2008 05:03:12 +0000

Be aware that the version of libxml2 included with Mac OS X to date is 2.6.16, which has a lot of bugs in xmlTextReader – in fact, several parts of it aren’t even implemented at all! None of this is documented, either, sadly, though all the issues I’m aware of are fixed in 2.6.32 (the latest).

If you’re stuck using it – though there are alternatives, if you don’t mind pulling in a 3rd party library – it’s worth pulling down the source for 2.6.16 (ftp://xmlsoft.org/libxml2/libxml2-2.6.16.tar.gz) and carefully checking out each function before you use them, to see if there’s any bits obviously missing. That won’t save you from the crashing bugs, alas.

By: schwa

schwa — Tue, 19 Aug 2008 02:57:46 +0000

While forgetting about NSXMLDocument & co you should not be forgetting TouchXML: http://code.google.com/p/touchcode/wiki/TouchXML – an Objective-C XML library that for some unknown reason manages to clone enough NSXMLDocument to be useful.