unity-towers-of-hanoi/Assets/Editor/AutoSave.cs

using UnityEngine;
using UnityEditor;
using UnityEditor.SceneManagement;

[InitializeOnLoad]
public class AutoSaveOnRunMenuItem
{
    public const string MenuName = "Tools/Autosave On Run";
    private static bool isToggled;

    static AutoSaveOnRunMenuItem()
    {
        EditorApplication.delayCall += () =>
        {
            isToggled = EditorPrefs.GetBool(MenuName, false);
            UnityEditor.Menu.SetChecked(MenuName, isToggled);
            SetMode();
        };
    }

    [MenuItem(MenuName)]
    private static void ToggleMode()
    {
        isToggled = !isToggled;
        UnityEditor.Menu.SetChecked(MenuName, isToggled);
        EditorPrefs.SetBool(MenuName, isToggled);
        SetMode();
    }

    private static void SetMode()
    {
        if (isToggled)
        {
            EditorApplication.playModeStateChanged += AutoSaveOnRun;
        }
        else
        {
            EditorApplication.playModeStateChanged -= AutoSaveOnRun;
        }
    }

    private static void AutoSaveOnRun(PlayModeStateChange state)
    {
        if (EditorApplication.isPlayingOrWillChangePlaymode && !EditorApplication.isPlaying)
        {
            Debug.Log("Auto-Saving before entering Play mode");

            EditorSceneManager.SaveOpenScenes();
            AssetDatabase.SaveAssets();
        }
    }