public ActionResult GetVersion()
 {
     try
     {
         AppVersion appVersion;
         using (var ctx=new DriverDBContext())
         {
             appVersion = ctx.AppVersions.OrderByDescending(x => x.VersionCode).FirstOrDefault();
         }
         var result = new GetVersionResponse()
         {
             VersionName = appVersion.VersionName,
             VersionCode = appVersion.VersionCode,
             DownloadUrl = Request.Url.Authority+"/apk/" + appVersion.FileName
         };
         return ApiResponse.OK(JsonConvert.SerializeObject(result));
     }
     catch (Exception)
     {
         return ApiResponse.UnknownError;
     }
 }