Grand Central Dispatch and NSXML Parser (the bad way)

GCD+NSXML-Bad.m

NSURL *xmlURL = [NSURL URLWithString:URL];
rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];
[rssParser setDelegate:self];
[rssParser setShouldProcessNamespaces:NO];
[rssParser setShouldReportNamespacePrefixes:NO];
[rssParser setShouldResolveExternalEntities:NO];
rssQueue = dispatch_queue_create("com.example.parser", NULL);
dispatch_async(rssQueue, ^{
[rssParser parse];
});

GCDNSXML-Bad.m

NSURL *xmlURL = [NSURL URLWithString:URL];
rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL];
[rssParser setDelegate:self];
[rssParser setShouldProcessNamespaces:NO];
[rssParser setShouldReportNamespacePrefixes:NO];
[rssParser setShouldResolveExternalEntities:NO];
rssQueue = dispatch_queue_create("com.example.parser", NULL);
dispatch_async(rssQueue, ^{
    [rssParser parse];
});