/// <summary>
/// 保存自定义消息
/// </summary>
/// <param name="conv_id">会话的 ID</param>
/// <param name="iMConvType">会话类型，请参考 TIMConvType</param>
/// <param name="msg">消息</param>
/// <param name="handler">保存自定义消息成功与否的回调</param>
public static TIMResult IMMsgSaveMsg(string conv_id, TIMConvType iMConvType, IMessage msg, MsgSaveMsgDelgate handler = null)
{
var ptr = DelegateConverter.ConvertToIntPtr(handler);
return((TIMResult)TIMClientAPIDef.TIMMsgSaveMsg(conv_id, iMConvType, JsonConvert.SerializeObject(msg), MsgSaveMsgResultCallBack, ptr));
}