設定をプレイ中に変更したり、jsonに書き込んだり、読み込んだり

Extensions.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

using System.IO;

static class Extensions
{

	public static void LoadJsonFile<T> (T overwriteTarget, string filePath = "appData.json")
	{
		var path = Path.Combine (Application.streamingAssetsPath, filePath);
		if (File.Exists (path))
			JsonUtility.FromJsonOverwrite (File.ReadAllText (path), overwriteTarget);
		else
			SaveJsonFile (overwriteTarget, filePath);
	}

	public static void SaveJsonFile<T> (T obj, string filePath = "appData.json")
	{
		var json = JsonUtility.ToJson (obj);
		var path = Path.Combine (Application.streamingAssetsPath, filePath);
		var dPath = Path.GetDirectoryName (path);
		if (!Directory.Exists (dPath))
			Directory.CreateDirectory (dPath);

		using (var writer = new StreamWriter (path))
			writer.Write (json);
		#if UNITY_EDITOR
		UnityEditor.AssetDatabase.Refresh ();
		#endif
	}
}

MySettingManager.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;
using System.Linq;

public class MySettingManager : MonoBehaviour
{
	public static void AddSettingMenu (Setting setting, string filePath)
	{
		setting.LoadSettingFromFile (filePath);
		if (!Instance.settings.Contains (setting)) {
			Instance.settings.Add (setting);
			Instance.settings = Instance.settings.OrderBy (b => b.filePath).ToList ();
		}
	}

	#region instance

	public static MySettingManager Instance {
		get { 
			if (_Instance == null)
				_Instance = new GameObject ("SettingManager").AddComponent<MySettingManager> ();
			return _Instance;
		}
	}

	static MySettingManager _Instance;

	#endregion

	public static KeyCode EditKey = KeyCode.E;

	List<Setting> settings = new List<Setting> ();
	Setting currentSetting;
	bool edit;
	Rect windowRect = Rect.MinMaxRect (0, 0, Math.Min (Screen.width, 1024f), Math.Min (Screen.height, 768f));
	Vector2 scroll;

	
	// Update is called once per frame
	void Update ()
	{
		if (Input.GetKeyDown (EditKey)) {
			edit = !edit;
			Cursor.visible = edit;
		}
	}

	void OnGUI ()
	{
		if (!edit)
			return;
		windowRect = GUI.Window (0, windowRect, OnWindow, "Settings");
	}

	void OnWindow (int id)
	{
		scroll = GUILayout.BeginScrollView (scroll);
		foreach (var setting in settings) {
			if (setting.edit) {
				GUILayout.BeginHorizontal ();
				GUILayout.Space (16f);
				GUILayout.BeginVertical ();
				GUILayout.Label (setting.filePath);
				setting.OnGUIFunc ();
				GUILayout.BeginHorizontal ();
				if (GUILayout.Button ("Save and Close"))
					setting.SaveAndClose ();
				if (GUILayout.Button ("Cancel"))
					setting.edit = false;
				GUILayout.EndHorizontal ();
				GUILayout.EndVertical ();
				GUILayout.EndHorizontal ();
			} else if (GUILayout.Button (setting.filePath))
				setting.edit = true;
		}
		GUILayout.EndScrollView ();
		GUI.DragWindow ();
	}

	[System.Serializable]
	public abstract class Setting
	{
		public string filePath{ get; set; }

		public bool edit{ get; set; }

		public abstract void OnGUIFunc ();

		public void LoadSettingFromFile (string path)
		{
			filePath = path;
			Extensions.LoadJsonFile (this, filePath);
			OnLoad ();
		}

		public void SaveAndClose ()
		{
			Extensions.SaveJsonFile (this, filePath);
			edit = false;
			OnClose ();
		}

		public void CancelAndClose ()
		{
			Extensions.LoadJsonFile (this, filePath);
			edit = false;
			OnClose ();
		}

		protected virtual void OnLoad ()
		{
		}

		protected virtual void OnClose ()
		{
		}
	}
}