Question

I have a method in my app to fetch a rss feed, and instruments shows that i’ve got a memory leak in my fetch method.

NSData* xmlData = [[NSMutableData alloc] initWithContentsOfURL:[NSURL URLWithString: kRSSUrl] ];
NSError *error;

GDataXMLDocument* doc = [[GDataXMLDocument alloc] initWithData:xmlData options:0 error:&error];

if (doc != nil) {
    self.loaded = YES;

    NSArray* items = [[doc rootElement] nodesForXPath:@"channel/item" error:&error];
    NSMutableArray* rssItems = [NSMutableArray arrayWithCapacity:[items count] ];

    for (GDataXMLElement* xmlItem in items) {
        [rssItems addObject: [self getItemFromXmlElement:xmlItem] ];
    }

    [self.delegate performSelectorOnMainThread:@selector(updatedFeedWithRSS:) withObject:rssItems waitUntilDone:YES];



} else {
    [self.delegate performSelectorOnMainThread:@selector(failedFeedUpdateWithError:) withObject:error waitUntilDone:YES];
}
[doc autorelease];
[xmlData release];

Instruments throw this:

---

Leaked Object   #   Address Size    Responsible Library Responsible Frame
Malloc 16 Bytes,4   < multiple >    64 Bytes    appname     -[RSSLoader fetchRss]

EDIT

My getItemFromXmlElement method:

-(NSDictionary*)getItemFromXmlElement:(GDataXMLElement*)xmlItem
{
    return [NSDictionary dictionaryWithObjectsAndKeys:
                          [[[xmlItem elementsForName:@"title"] objectAtIndex:0] stringValue], @"title",
                          [[[xmlItem elementsForName:@"link"] objectAtIndex:0] stringValue], @"link",
                          [[[xmlItem elementsForName:@"description"] objectAtIndex:0] stringValue], @"description",
                          nil];
}

Answer 1

Instruments is not telling you that this routine leaked, only that one of the objects created in this routine was leaked.

My guess is the rssItems array passed to updatedFeedWithRSS is over-retained at some point, by either updatedFeedWithRSS or something it calls. Us verifying this would take posting a lot of code, and it’s not worth it. Just read through and see if you can find it.