RAC: async request factory method returning a RACSignal

gistfile1.m

- (RACSignal *)enqueueRequestWithMethod:(NSString *)method
                                   path:(NSString *)path
                             parameters:(NSDictionary *)parameters
{
    RACReplaySubject *subject = [RACReplaySubject subject];
    NSURLRequest *request = [self requestWithMethod:method path:path parameters:parameters];
    AFHTTPRequestOperation *operation = [self HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, id responseObject) {
        [subject sendNext:responseObject];
        [subject sendCompleted];
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        [subject sendError:error];
    }];

    [self enqueueHTTPRequestOperation:operation];

    return subject;
}