Sorry this is a little late, but I think this is what youre looking for (courtesy of the AFNetworking ReadMe on Github) :
AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
[manager GET:@"http://example.com/resources.json" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(@"Error: %@", error);
}];
Then, if you need to, you can then convert responseData into NSData using (source):
NSData *myData = [NSKeyedArchiver archivedDataWithRootObject:responseObject];