Is it safe to use the "hash" method to track NSURLConnections in memory?

Question

My question is related to this discussion: http://www.cocoabuilder.com/archive/cocoa/202211-how-to-get-nsurl-form-nsurlconnection.html

I am sending several NSURLConnections to transmit data and need to be able to tell which specific connection failed or succeeded. There are NSURLDelegate methods (didFailWithError, etc) which return the related NSURLConnection. The problem is that there is no NSURLRequest returned in the delegate methods (and there is no NSURL accessor in the NSURLConnection).

The solution I've implemented is to maintain a NSMutableDictionary which pairs the URL string that was sent with the result of this NSURLConnection's "hash" method.

I've tested it and it seems to work - the hash of the NSURLConnection that is returned in the delegate method is the same as the hash from the NSURLConnection that was sent initially.

My question: is it safe to do this? Is there a better key to use than the hash? I'm asking because in my naive understanding, the hash is somehow associated with the address of that object in the memory, and it seems possible that backgrounding the app or turning the phone off and on may change this value as things are rewritten to memory.

Thanks very much!

Answer 1

I generally use ASIHTTPRequest, and when issuing multiple connections (concurrently in queue or parallel) I use the userInfo dictionary to pass around context.

The "hash IVAR" you refer to is actually defined in the NSObject protocol - as a method. It is intended to be used in a hash table, and as such should be sufficient for your needs.

I'd still prefer a more first-class approach to this problem, whilst making it more explicit which request is finishing/erroring-out.