- (void)connectionNSURLConnection *)connection didReceiveResponseNSURLResponse *)response{

    NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *)response;

    if(httpResponse && [httpResponse respondsToSelectorselector(allHeaderFields)]){

        NSDictionary *httpResponseHeaderFields = [httpResponse allHeaderFields];

        total_ = [[httpResponseHeaderFields objectForKey"Content-Length"] longLongValue];

        //NSLog(@"%lld", total_);

    }

}