Question

I am trying to call objectForKey: on an nsdictionary ivar, but I get an EXC_BAD_ACCESS error.
The nsdictionary is created using the JSON-framework and then retained. The first time I use it (just after I create it, same run loop) it works perfectly fine, but when I try to access it later nothing works. I am doing this code to try to figure out what is wrong:

if (resultsDic == nil) {
    NSLog(@"results dic is nil.");
}
if ( [resultsDic respondsToSelector:@selector(objectForKey:)] ) {
    NSLog(@"resultsDic should respond to objectForKey:");
}

The dictionary is never nil, but it always crashes on respondsToSelector. any ideas?

addition:
These are the other places, besides above, that the dictionary gets interacted with:

- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    [connection release];

    //get the data in a usable form
    NSString *jsonString = [[NSString alloc] initWithData:downloadedData encoding:NSUTF8StringEncoding];
    resultsDic = [jsonString JSONValue];

    [self processResults];

    NSLog(@"Success. Received %d bytes of data",[downloadedData length]);
    [downloadedData release];
    [jsonString release];
}



- (void)processResults
{
        NSArray *resultsArr = [resultsDic objectForKey:@"results"];
                CLLocationCoordinate2D coordinate = [self coordinateFromResult:[resultsArr objectAtIndex:0]];
        NSLog(@"lat: %f lng: %f", coordinate.latitude, coordinate.longitude);
}

- (void)dealloc {
  [resultsDic release];
  [super dealloc];
}

Answer 1

After somethings retain count is decreased to 0, the object gets deallocated. This is not the same as setting it to nil. It will not be nil. Whilst you can send messages to nil, sending a message to a released object will result in an EXC_BAD_ACCESS error. If you post some of the code where it is created and used, maybe we can help you debug it. Try retaining it twice at the beginning. it’s nit an elegant solution, but it might work as a quick fix.