断网失败也有回调的，有完整点的代码吗？

        AFHTTPRequestSerializer * requestSerializer = [AFHTTPRequestSerializer serializer];
        [requestSerializer setTimeoutInterval:20.0f];
        request = [requestSerializer multipartFormRequestWithMethod:@”POST”
                                                                             URLString:urlString
                                                                            parameters:parameter
                                                             constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {}
                                                                                 error:nil];

            AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
            [manager.requestSerializer setTimeoutInterval:20.0f];
            [manager HTTPRequestOperationWithRequest:request success:^(AFHTTPRequestOperation *operation, id responseObject) {
                //method1
            } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
                //method2
            }];
拔掉网线，然后发送请求，method1 和method2都没调用.hud没法隐藏，很多人通过，判断网络状态来隐藏HUd的。