__builtin_va_arg (for pointer to pointer)

问题

I have a code which extracts the arguments of a method.

va_list argp2; 
va_start(argp2, sel);

NSURLResponse* obj = va_arg(*argp2,NSURLResponse**);

the argp2 contains the arguments for the method [NSURLConnection sendSynchronousRequest:urlRequest returningResponse:&response error:&error]

I would like to convert argp2 to get a pointer to response and error objects.

Thanks

来源：https://stackoverflow.com/questions/23741425/builtin-va-arg-for-pointer-to-pointer