Question

(tl;dr: see summary at the bottom.)

I am implementing an application that pulls content from an RSS feed off a single site. Here is a sample of the XML:

<item>
<title>Title</title>
<link>http://example.com</link>
<comments>http://example.com/#comments</comments>
<pubDate>Thu, 26 Jan 2012 03:05:11 +0000</pubDate>
<dc:creator>Billy D. Author</dc:creator> 
<category><![CDATA[sample_category]]></category>

<guid isPermaLink="false">http://example.com</guid>
<description><![CDATA[Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras ac erat nec odio cursus accumsan. Nam feugiat hendrerit neque, nec tristique nisl ullamcorper vel. Nullam pellentesque augue metus. Vestibulum in lectus orci, eget ornare felis.&#8230;]]></description>
<content:encoded><![CDATA[<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras ac erat nec odio cursus accumsan. Nam feugiat hendrerit neque, nec tristique nisl ullamcorper vel. Nullam pellentesque augue metus. Vestibulum in lectus orci, eget ornare felis. Vestibulum nisl lacus, faucibus ac aliquet eu, pellentesque rutrum justo. Nulla fringilla venenatis augue a laoreet. Maecenas metus leo, euismod eget rutrum in, mattis eget nisi. Proin at massa sit amet odio tempor venenatis sit amet sit amet erat. Mauris vitae bibendum arcu. Curabitur a purus vitae ipsum ultricies luctus vel et velit.</p><p>Donec in lacus sit amet mi sagittis auctor eget nec nunc. Pellentesque adipiscing venenatis risus, a faucibus sem pretium quis. Nam fringilla metus eu nulla pellentesque semper. Quisque in lectus nisi. Fusce pretium accumsan purus nec sodales. Donec velit nisi, ullamcorper at faucibus vitae, lacinia quis dui. Duis eu dui leo, eget varius diam. Aliquam imperdiet volutpat tellus quis venenatis. Vivamus laoreet malesuada tincidunt. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus. Mauris ut purus est. Sed quis mauris ut dolor dapibus vestibulum ut eu dolor. Cras interdum sagittis faucibus. Nulla tortor ligula, molestie at sollicitudin at, hendrerit et lacus. Nunc lorem enim, aliquet id porttitor ultrices, sodales ac sapien.</p>]]></content:encoded>
<wfw:commentRss>http://example.com/feed/</wfw:commentRss>
<slash:comments>0</slash:comments>
<enclosure url="http://example.com/some/other/stuff/>
</item>

I am interested in the following elements: title, link, pubDate, dc:creator, description, content:encoded.

As you might guess, title, link, pubDate and description pull just fine. But instead of any of the content of dc:creator I get that of pubDate, and instead of content:encoded, I get description.

For my parser object, I have

[xmlParser setDelegate:self];

[xmlParser setShouldProcessNamespaces: YES];
[xmlParser setShouldReportNamespacePrefixes:YES];
[xmlParser setShouldResolveExternalEntities:YES];

and have implemented the following methods:

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {

    // NSLog(@"element %@, ns %@, qn %@", elementName, namespaceURI, qName);

    if ( [elementName isEqualToString:@"rss"] ) {
    return;
}

if ( [elementName isEqualToString:@"channel"] ) {
    // begin the set of entries
    if (!allEntries)
        allEntries = [NSMutableArray array];
    return;
}

if ( [elementName isEqualToString:@"item"] ) {
    // item means a new post!
    // currentPost = [[DIDSEntry alloc] init]; 
    return;
}

if ( [elementName isEqualToString:@"title"]) {
    [self setCurrentProperty:@"title"];
    currentPostTitle = [NSString string];
    return;
}

if ( [elementName isEqualToString:@"link"] ) {
    [self setCurrentProperty:@"url"];
    currentPostUrl = [[NSURL alloc] init];
    return;
}

if ( [elementName isEqualToString:@"pubDate"] ) {
    [self setCurrentProperty:@"date"];
    currentPostDate = [[NSDate alloc] init];
    return;
}

if ( [elementName isEqualToString:@"dc:creator"] ) {
    [self setCurrentProperty:@"author"];
    currentPostAuthor = [NSString string];
    return;
}

if ( [elementName isEqualToString:@"description"] ) {
    [self setCurrentProperty:@"preview"];
    currentPostPreview = [NSString string];
    return;
}

if ( [elementName isEqualToString:@"content:encoded"] ) {
    [self setCurrentProperty:@"text"];
    currentPostText = [NSString string];
    return;
}

}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
if (!currentStringValue) {
    // currentStringValue is an NSMutableString instance variable
    currentStringValue = [[NSMutableString alloc] initWithCapacity:50];
}
[currentStringValue appendString:string];
}
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {

if ( [elementName isEqualToString:@"rss"] ) {
    return;
}
if ( [elementName isEqualToString:@"channel"]) return;

if ( [elementName isEqualToString:@"item"] ) {
    currentPost = [[DIDSEntry alloc] initWithPostTitle:currentPostTitle postAuthor:currentPostAuthor postUrl:currentPostUrl pubDate:currentPostDate postPreview:currentPostPreview postText:currentPostPreview];
    [allEntries addObject:currentPost];
    return;
}
NSString *prop = [self currentProperty];

if ( [prop isEqualToString:@"title"] ) {
    [self setCurrentPostTitle:currentStringValue];
    // return;
}

if ( [prop isEqualToString:@"url"] ) {
    [self setCurrentPostUrl:[NSURL URLWithString:currentStringValue]];
    // return;
}

if ( [prop isEqualToString:@"date"] ) {
    NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"EEE, d MMM yyyy HH:mm:ss ZZZ"];
    [self setCurrentPostDate:[formatter dateFromString:currentStringValue]];
    // NSLog(@"date: %@", currentStringValue);
}

if ( [prop isEqualToString:@"author"] ) {
    [self setCurrentPostAuthor:currentStringValue];
    // return;
}

if ( [prop isEqualToString:@"preview"] ) {
    [self setCurrentPostPreview:currentStringValue];
    // return;
}

if ( [prop isEqualToString:@"text"] ) {
    [self setCurrentPostText:currentStringValue];
    // return;
}
// currentStringValue is an instance variable
currentStringValue = nil;

return;
}

I’ve also kind of implemented

- (void)parser:(NSXMLParser *)parser didStartMappingPrefix:(NSString *)prefix toURI:(NSString *)namespaceURI

and

- (void)parser:(NSXMLParser *)parser didEndMappingPrefix:(NSString *)prefix

but only to log that they’re being called (they are) since I don’t know what I’m even supposed to do with them.

I’ve been all over the web trying to find an answer to why my code is behaving like this and how I might fix it but I’m completely at a loss. I tried testing for qualified names instead of element names, lopping off the prefixes, and a few other things, but no joy. (I also only superficially understand XML namespaces, though everything I’ve seen hasn’t really addressed what I’m after.)

In summation:

Trying to parse elements with namespaces and store their contents in instance variables results in the previously parsed elements being stored in those ivars. I have no idea why that’s the case and how it can be fixed.

Answer 1

Solved. Please forgive me, but apparently this post is only tangentially related to namespaces. I did take the namespace prefixes off the element names when I checked for them, set the currentProperty string to nil after each use and noticed that I was setting the postText to currentPostPreview. Sorry. It was late.