AFNetworking: Access to completion handlers when retrying operation

Question

To give some context: I'm trying to implement a global error handler for authentication errors (using token authentication, not basic), which should try to re-authenticate and then repeat the original failed request (see my previous question: AFNetworking: Handle error globally and repeat request)

The current approach is to register an observer for the AFNetworkingOperationDidFinishNotification which does the re-authentication and (if auth succeeded) repeats the original request:

- (void)operationDidFinish:(NSNotification *)notification
{
    AFHTTPRequestOperation *operation = (AFHTTPRequestOperation *)[notification object];

    if(![operation isKindOfClass:[AFHTTPRequestOperation class]]) {
        return;
    }

    if(403 == [operation.response statusCode]) {
        // try to re-authenticate and repeat the original request
        [[UserManager sharedUserManager] authenticateWithCredentials...
            success:^{
                // repeat original request

                // AFHTTPRequestOperation *newOperation = [operation copy]; // copies too much stuff, eg. response (although the docs suggest otherwise)
                AFHTTPRequestOperation *newOperation = [[AFHTTPRequestOperation alloc] initWithRequest:operation.request];

                // PROBLEM 1: newOperation has no completion blocks. How to use the original success/failure blocks here?

                [self enqueueHTTPRequestOperation:newOperation];
            }
            failure:^(NSError *error) {
                // PROBLEM 2: How to invoke failure block of original operation?
            }
        ];
    }
}

However, I stumbled upon some issues regarding completion blocks of request operations:

• When repeating the original request, I obviously want its completion blocks to be executed. However, AFHTTPRequestOperation does not retain references to the passed success and failure blocks (see setCompletionBlockWithSuccess:failure:) and copying NSOperation's completionBlock is probably not a good idea, as the documentation for AFURLConnectionOperation states:

  Operation copies do not include completionBlock. completionBlock often strongly captures a reference to self, which, perhaps surprisingly, would otherwise point to the original operation when copied.

• In case the re-authentication fails, I want to call the original request's failure block. So, again, I'd need direct access to this.

Am I missing something here? Any ideas for alternative approaches? Should I file a feature request?

Answer 1

I've come up with this problem in Art.sy's portfolio app. My eventual conclusion was to create a NSOperationQueue subclass which had functions to create copies of various AFNetworking HTTP Operations once they failed (and to do this up to three times per URL before giving up.)