JsonTest.cs

using UnityEngine;
using System.Runtime.Serialization.Formatters.Binary;
using System.IO;

public class JsonTest : MonoBehaviour
{
    //---
    [System.Serializable]
    public class Item
    {
        public int id;
        public string name;
        public string description;
    }

    //---
    string savePath = "Assets/Test/JsonTest/saveData.json";

    // Use this for initialization
    void Start ()
    {
        string itemJson = "{ \"id\": 100, \"name\": \"テストアイテム\", \"description\": \"説明だよ\" }";
        Item item = JsonUtility.FromJson<Item>(itemJson);

        save(item);
        TestLog(item);

        Debug.Log("---");

        item = load();
        TestLog(item);
    }

    //セーブ
    private void save(Item item)
    {
        string json = JsonUtility.ToJson(item);
        BinaryFormatter bf = new BinaryFormatter();
        FileStream file = File.Create(savePath);
        bf.Serialize(file, json);
        file.Close();
    }

    //ロード
    private Item load()
    {
        BinaryFormatter bf = new BinaryFormatter();
        FileStream file = File.Open(savePath, FileMode.Open);
        string json = (string)bf.Deserialize(file);
        file.Close();
        return JsonUtility.FromJson<Item>(json);
    }

    //確認用のログを表示
    private void TestLog(Item item)
    {
        Debug.Log("item id " + item.id);
        Debug.Log("item name " + item.name);
        Debug.Log("item description " + item.description);
    }
}