Manage Assetbundles for unity3d

AssetBundleManager.cs

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

public class AssetBundleManager {
	class AssetReference : IDisposable {
		int count;
		public AssetBundle bundle;
		
		public AssetReference(AssetBundle bundle) {
			this.bundle = bundle;
			this.count = 0;
		}
		
		public int Increase() {
			return ++count;
		}
		
		public int Decrease() {
			--count;
			if(count <= 0) {
				this.Dispose();
			}
			return count;
		}
		
		public void Dispose() {
			if(bundle!=null) {
				bundle.Unload(false);
				bundle = null;
			}
		}
	}
	
	static Dictionary<string,AssetReference> bundles = new Dictionary<string,AssetReference>();
	
	static public void AddAssetBundle(string url, AssetBundle bundle){
		if(bundles.ContainsKey(url)) {
			bundles[url].Increase();
		}
		else {
			bundles.Add(url, new AssetReference(bundle));
		}
	}
	
	static public void AddAssetBundle(WWW www) {
		AddAssetBundle(www.url, www.assetBundle);
	}
	
	static public void DeleteAssetBundle(string url) {
		if(bundles.ContainsKey(url)) {
			if(bundles[url].Decrease() <= 0) {
				bundles.Remove(url);
			}
		}
	}
	
	static public void DeleteAssetBundle(WWW www) {
		DeleteAssetBundle(www.url);
	}
	
	static public AssetBundle GetAssetBundle(string url) {
		if(bundles.ContainsKey(url)) {
			return bundles[url].bundle;
		}
		else {
			return null;
		}
	}
	
	static public bool HasAssetBundle(string url) {
		if(bundles.ContainsKey(url)) {
			return true;
		}
		else {
			return false;
		}
	}
}

How To Use

// マネージャーに参照を追加
AssetBundleManager.AddAssetBundle(www);

// マネージャーから参照を削除
AssetBundleManager.DeleteAssetBundle(url);
// マネージャーないで、同アセットバンドルへの参照数が０になったら、アンロードします。

// アセットバンドルを取得
AssetBundleManager.GetAssetBundle(url);