NSArray *PerformXPathQuery(xmlDocPtr doc, NSString *query)
{
xmlXPathContextPtr xpathCtx;
xmlXPathObjectPtr xpathObj;

/* Create xpath evaluation context */
xpathCtx = xmlXPathNewContext(doc);
if(xpathCtx == NULL)
{
NSLog(@"Unable to create XPath context.");
return nil;
}

/* Evaluate xpath expression */
xpathObj = xmlXPathEvalExpression((xmlChar *)[query cStringUsingEncoding:NSUTF8StringEncoding], xpathCtx);
if(xpathObj == NULL) {
NSLog(@"Unable to evaluate XPath.");
return nil;
}

xmlNodeSetPtr nodes = xpathObj->nodesetval;
if (!nodes)
{
NSLog(@"Nodes was nil.");
return nil;
}

NSMutableArray *resultNodes = [NSMutableArray array];
for (NSInteger i = 0; i < nodes->nodeNr; i++)
{
NSDictionary *nodeDictionary = DictionaryForNode(nodes->nodeTab[i], nil);
if (nodeDictionary)
{
[resultNodes addObject:nodeDictionary];
}
}

/* Cleanup */
xmlXPathFreeObject(xpathObj);
xmlXPathFreeContext(xpathCtx);

return resultNodes;
}

if (!nodes)
{
NSLog(@"Nodes was nil.");
/* Cleanup */
xmlXPathFreeObject(xpathObj);
xmlXPathFreeContext(xpathCtx);
return nil;
}