var client = new Baidu.Aip.Face.Face(Api_Key, Secret_Key);
var image = ImgToBase64String(bitmap);

var imageType = "BASE64";

var groupIdList = "3,2";

// 调用人脸搜索，可能会抛出网络等异常，请使用try/catch捕获
var result = client.Search(image, imageType, groupIdList);

返回结果base {Newtonsoft.Json.Linq.JContainer} = {"error_code": 222207,"error_msg": "match user is not found","log_id": 2510558289,"timestamp": 1529119362,"cached": 0,"result":null}总是提示未找到，同一个userId下已经放了3张图了，可还是提示这样的返回结果