Question

I’ve the following problem:

I’m accessing foursquares Venue API and get a JSON string back. I parse this string with this json-framework. After that I’m saving the dictionaries and arrays for accessing further information about the venues (in special I’m using the explore API). So the venue information is saved deeply (for my experience) in the json-structure tree. And after getting the needed information (venue name & coordinates) I put a corresponding pin on a map with the same coordinates and with the venue’s name as the pin’s name.

And exactly at the point where I want to set the pin’s name, I get a memory leak. So something get’s wrong here. If I don’t set any title, all works fine. So the memory leak occurs only when I’m setting the name of the venue to the pin.

Here is the corresponding code fragment:

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    //Parse JSON string
    // Store incoming data into a string
    NSString *jsonString = [[NSString alloc] initWithData:self.fetchedJSONData encoding:NSUTF8StringEncoding];
    [self.fetchedJSONData setLength:0];

    // Create a dictionary from the JSON string     
    NSDictionary *results = [NSDictionary dictionaryWithDictionary:[jsonString JSONValue]];
    [jsonString release];

    NSDictionary *response = [NSDictionary dictionaryWithDictionary:[results objectForKey:@"response"]];

    NSArray *groups = [NSArray arrayWithArray:[response objectForKey:@"groups"]];
    NSDictionary *groupsDic = [groups lastObject];
    NSArray *items = [NSArray arrayWithArray:[groupsDic objectForKey:@"items"]];

   for (int i=0; i<[items count]; i++)
   {
        CLLocationCoordinate2D annotationCoord;
        MKPointAnnotation *annotationPoint = [[MKPointAnnotation alloc] init];
        NSDictionary* oneItemDoc = [NSDictionary dictionaryWithDictionary:[items objectAtIndex:i]]; 
        NSDictionary *singleVenue = [NSDictionary dictionaryWithDictionary:[oneItemDoc objectForKey:@"venue"]];             

        /*
         *          Leak here in the next two lines!
         *
         */

        NSString *titleName = [[[singleVenue objectForKey:@"name"] copy] autorelease]; 
        annotationPoint.title = titleName;

        NSDictionary *locationOfVenue = [NSDictionary dictionaryWithDictionary:[singleVenue objectForKey:@"location"]];

        annotationCoord.latitude = [[locationOfVenue objectForKey:@"lat"] doubleValue];
        annotationCoord.longitude = [[locationOfVenue objectForKey:@"lng"] doubleValue];               
        annotationPoint.coordinate = annotationCoord;

        [self.mapView addAnnotation:annotationPoint];
        [self.annotationsArray addObject:annotationPoint];
        [annotationPoint release];
   }
}

So the leak occurs when I want to set the title for the annotationPoint.

For each venue fetched with JSON I get the following leak trace (blurred libraries are my own libraries):

Has anybody a suggestion how to solve this problem? I tried many, many things. So the key issue seems to be how to “hand over” the [singleVenue objectForKey:@"name"] correctly. I first tried to set it without a copy and an autorelease, but then I get a zombie object. So I don’t know how to do this. I think the problem are not these two lines, but some lines above them. Am I right? I also have the suggestion, that my 3rd party json parser is forcing this problem (cf. leak trace).

So I hope someone can help me to fix this problem. Would be really great!

Update: The problem seems to be independent of the corresponding JSON parser. I’ve testet my code with another parser, same problem there. So it has to do something with my code itself.

I think I know what’s the problem. So the leak occurs after closing the map. So after dealloc. So it might be, that I’ve missed something there. I have a mapview and I also release it in dealloc and set it to nil in viewDidUnload. I also release all the other Arrays etc. in dealloc. Is there something else (specific about the map and view) which I need to release? I think this might be the problem!

Update: Solved the problem: I had to set all Foursquare pins’ title and subtitle to nil in the dealloc method, because a value (accessed via a JSON parser) was retained by the map view somehow. Now all works fine!

Answer 1

Solved the problem: I had to set all Foursquare pins’ title and subtitle to nil in the dealloc method, because a value (accessed via a JSON parser) was retained by the map view somehow. Now all works fine!