Unity3D: Somewhat Hacky Method for Auto Saving Assets in Unity.

AutoSaveAssets.cs

//#define VERBOSE
/* ***************************************************************************
   Copyright 2011 Calvin Rien
   (http://the.darktable.com)

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

*************************************************************************** */

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

[InitializeOnLoad]
public class OnUnityLoad {
	static OnUnityLoad() {
		if (AutoSaveAssets.instance == null)
			AutoSaveAssets.instance = ScriptableObject.CreateInstance<AutoSaveAssets>();
	}
}

/// <summary>
/// Drop this into a folder called "Editor" in your Unity project (or Plugins/Editor, or Standard Assets/Editor).
///
/// This should autosave modified assets (Materials, Prefabs, etc.) every "interval" seconds, unless you are
/// running the game in the editor.
/// </summary>
public class AutoSaveAssets : ScriptableObject {
	static int interval = 300;
	static uint lastRun = 0;

	public static AutoSaveAssets instance;

	void OnEnable() {
		if (instance != null && instance != this) {
			DestroyImmediate(this);
			return;
		}
		instance = this;
		lastRun = (uint)EditorApplication.timeSinceStartup;

		EditorApplication.update += EditorUpdate;
	}

	void OnDisable() {
		if (instance == this)
			EditorApplication.update -= EditorUpdate;
	}

	static void EditorUpdate() {
		var seconds = (uint)EditorApplication.timeSinceStartup;
		
		if (seconds - lastRun >= interval && SaveAssets()) {
			lastRun = seconds;
		}
	}

	static bool SaveAssets() {
		if (EditorApplication.isPlayingOrWillChangePlaymode || EditorApplication.isCompiling || EditorApplication.isPaused)
			return false;
#if VERBOSE
		Debug.Log(string.Format("=== auto saving @ {0} ===", System.DateTime.Now.ToLongTimeString()));
#endif
		EditorApplication.SaveAssets();
		return true;
	}
}