using System;
using UnityEngine;
using System.Collections;

public class CachingLoadExample : MonoBehaviour {
    public string BundleURL;
    public string AssetName;
    public int version;

    void Start() {
        StartCoroutine (DownloadAndCache());
    }

    IEnumerator DownloadAndCache (){
       // Wait for the Caching system to be ready
       while (!Caching.ready)
            yield return null;

        // Load the AssetBundle file from Cache if it exists with the same version or download and store it in the cache
        using(WWW www = WWW.LoadFromCacheOrDownload (BundleURL, version)){
            yield return www;
            if (www.error != null)
                throw new Exception("WWW download had an error:" + www.error);
            AssetBundle bundle = www.assetBundle;
            if (AssetName =="")
                Instantiate(bundle.mainAsset);
            else
                Instantiate(bundle.Load(AssetName));
            // Unload the AssetBundles compressed contents to conserve memory
                    bundle.Unload(false);

        } // memory is freed from the web stream (www.Dispose() gets called implicitly)
    }
}

using UnityEditor;

public class CreateAssetBundles
{
     [MenuItem ("Assets/Build AssetBundles")]
     static void BuildAllAssetBundles ()
     {
         BuildPipeline.BuildAssetBundles ("Assets/AssetBundles");
     }
}