The HTTP Request class/wrapper

HTTPRequest.hpp

template <typename DoneLambda, typename ErrorLambda>
class HTTPRequest
{
public:
  HTTPRequest(const std::string& rURL,
              DoneLambda&& rDone,
              ErrorLambda&& rError)
  : mURL(rURL),
    mDone(std::forward<DoneLambda>(rDone)),
    mError(std::forward<ErrorLambda>(rError))
  {
  }
  
  auto operator()() noexcept -> void
  {
    auto url = [NSURL URLWithString:
                  [NSString stringWithUTF8String:mURL.c_str()]];
    auto session = [NSURLSession sharedSession];
    // Copy attributes for this block.
    __block auto done_lambda = mDone;
    __block auto error_lambda = mError;
    auto task = [session dataTaskWithURL:url            
                       completionHandler:
    ^(NSData *data, NSURLResponse *response, NSError *error)
     {
       auto httpResponse = (NSHTTPURLResponse *) response;
       // Error!
       if (error != nil || httpResponse == nil ||
           httpResponse.statusCode != 200 || data == nil)
       {
         // Force-dispatch on main thread          
         dispatch_async(dispatch_get_main_queue(),
         ^{ 
           error_lambda([[error localizedDescription] UTF8String]);
          });
       }
       else // Success! Pass the buffer and length to the lambda
       {
         __block const auto len = data.length;
         __block auto buf = std::unique_ptr<char[]>(new char[len]);
         memcpy(buf.get(), data.bytes, len);
         dispatch_async(dispatch_get_main_queue(),
         ^{ 
            done_lambda(std::move(buf), len);
          });
       }
    }
  }];
 [task resume];
}
private:
  const std::string mURL;
  DoneLambda mDone;
  ErrorLambda mError;
};