using System;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        CheckIsUpdate("{\"_isUpdate\":\"true\"}");

        CheckIsUpdate("{\"_isUpdate\":\"false\"}");

    }

    private static void CheckIsUpdate(string json)

    {

        var def = new { _isUpdate = true };

        var obj = JsonConvert.DeserializeAnonymousType(json, def);

​

        Console.WriteLine(obj._isUpdate);

    }

}