iPhone: ASIHTTP setDidFinishSelector issue - iphone

Question

I have the following code:
- (void)imageDownloaded:(ASIHTTPRequest *) request idPlace:(NSNumber *)idPlace
NSData *responseData = [request responseData];
if (responseData == nil) {
NSLog(#"bad");
}
}
And
NSURL *url = [NSURL URLWithString:[item objectForKey:#"image"]];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request setDidFinishSelector:[self performSelector:#selector(imageDownloaded:idPlace:)withObject:request withObject:place.idPlace]];
But it doesn't works because the responseData is null.
I have tried this way (with a selector with only one argument):
[request setDidFinishSelector:#selector(imageDownloaded:)];
- (void)imageDownloaded:(ASIHTTPRequest *) request
And this works. But i need to know the idPlace in order to save the image with the respective name to get later the image.
Any idea about how can i do this? Since selector with two arguments doesn't work i cannot find the solution to my question.

Answer 1

This line is garbage:
[request setDidFinishSelector:[self performSelector:#selector(imageDownloaded:idPlace:)withObject:request withObject:place.idPlace]];
This should be throwing a compiler warning at the very least. You're executing -imageDownloaded:idPlace: immediately, and then taking the result (which in your case is going to be whatever garbage value was on the stack) and returning that as the selector. the response data is nil because you're actually executing your imageDownloaded: method before the request even runs.
Assuming ASIHTTPRequest only accepts didFinishSelectors of the form foo: (e.g. one argument), then there's no good way to do what you're trying to do, which is to attach a second argument onto the method. That simply won't work. You have a few alternatives, but the simplest one is probably to make use of ObjC Associated Objects. You can hang your place.idPlace object off of the request and get at it later.
At the top of your file, define a key:
static char kAssociationKey; // we just want its memory location
Then when you start the request you can run:
objc_setAssociatedObject(request, &kAssociationKey, place.idPlace, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
[request setDidFinishSelector:#selector(imageDownloaded:)];
This will attach place.idPlace to the request object. Then in your didFinishSelector you can run
id oldIdPlace = objc_getAssociatedObject(request, &kAssociationKey);

Answer 2

You can use
[request setTag:place.idPlace]
to set Place ID
and
[request tag]
to get it in your imageDownloaded