public async Task MarkUnreadChatMessagesAsync(string userId, string roomId, IEnumerable<string> messageIds)
{
string url = _baseApiAddress + $"user/{userId}/rooms/{roomId}/unreadItems";
#if __IOS__ || __ANDROID__ || NET45
var content = new StringContent("{\"chat\": " + JsonConvert.SerializeObject(messageIds) + "}",
Encoding.UTF8,
"application/json");
#endif
#if NETFX_CORE
var content = new HttpStringContent("{\"chat\": " + JsonConvert.SerializeObject(messageIds) + "}",
UnicodeEncoding.Utf8,
"application/json");
#endif
await HttpClient.PostAsync(url, content);
}