如何在Windows Phone 8应用程序（非Web应用程序）中将Json数据发送到Web服务器？

Question

我的示例代码不能正常工作.....

WebClient webClient = new WebClient();
webClient.UploadStringCompleted += client_UploadStringCompleted;
webClient.Headers[HttpRequestHeader.ContentType] = "application/json";
string jsonData = JsonConvert.SerializeObject(imagesInfo);
webClient.UploadStringAsync(ImpressionUri, "POST", jsonData);