Unity提供了JSON序列化相关的的工具类JsonUtility，性能比.Net的Json要好。

目前只支持MonoBehaviour，ScriptableObject，与普通Class。普通Class要标识可序列化。

同时，字段的要求与ScriptableObject的要求一致，比如不支持Dictionary的序列化。

public static string ToJson(object obj);
public static string ToJson(object obj, bool prettyPrint);
public static T FromJson(string json);
public static void FromJsonOverwrite(string json, object objectToOverwrite);

[Serializable]
public class GameData
{
    public string[] Names;
    public int ID;
    public Dictionary<string, string> Cache;
}

void Start()
{
    GameData gd = new GameData ();
    gd.Names = new string[]{ "wxl", "nick" };
    gd.ID = 2008;
    gd.Cache = new Dictionary<string, string> ();
    gd.Cache.Add ("a", "aa");

    string str = JsonUtility.ToJson (gd);
    Debug.Log (str);

    GameData gd2 = JsonUtility.FromJson<GameData> (str);
    Debug.Log (gd2.Cache == null);  // Dictionary为空
    Debug.Log (gd2.Names);
    Debug.Log (gd2.ID);
}

https://docs.unity3d.com/560/Documentation/Manual/JSONSerialization.html