Unity3d 5.x AssetBoundle加载

上一篇讲了assetboundle的打包，这篇我们讲assetboundle的加载
其实加载过程也很简单，通过www加载或者通过AssetBundle.LoadFromFile加载，www可以加载网络资源，而AssetBundle.LoadFromFile不能加载网络资源。
加载assetboundle的方式有以下几种：

AssetBundle.LoadFromMemoryAsync
AssetBundle.LoadFromFile
WWW.LoadfromCacheOrDownload
UnityWebRequest’s DownloadHandlerAssetBundle (Unity 5.3 or newer)

第一种方式：

IEnumerator LoadFromMemoryAsync(string path)
    {
        AssetBundleCreateRequest createRequest = AssetBundle.LoadFromMemoryAsync(File.ReadAllBytes(path));
        yield return createRequest;
        AssetBundle bundle = createRequest.assetBundle;
        var prefab = bundle.LoadAsset.("MyObject");
        Instantiate(prefab);

    }

第二种：

using UnityEngine;
using System.Collections;
public class LoadFromFileExample : MonoBehaviour
{
    void Start()
    {
        var myLoadedAssetBundle = AssetBundle.LoadFromFile(Path.Combine(Application.streamingAssetsPath, "myassetBundle"));
        if (myLoadedAssetBundle == null)
        {
            Debug.Log("Failed to load AssetBundle!");
            return;
        }
        var prefab = myLoadedAssetBundle.LoadAsset("MyObject");
        Instantiate(prefab);
        myLoadedAssetBundle.Unload(false);
    }
}

第三种（网络下载相关的boundle）：

using UnityEngine;
using System.Collections;

public class LoadFromCacheOrDownloadExample : MonoBehaviour
{
    IEnumerator Start ()
    {
            while (!Caching.ready)
                    yield return null;
        var www = WWW.LoadFromCacheOrDownload("http://myserver.com/myassetBundle", 5);
        yield return www;
        if(!string.IsNullOrEmpty(www.error))
        {
            Debug.Log(www.error);
            yield return;
        }
        var myLoadedAssetBundle = www.assetBundle;
        var asset = myLoadedAssetBundle.mainAsset;
    }
}

第四种：

IEnumerator InstantiateObject()

    {
        string uri = "file:///" + Application.dataPath + "/AssetBundles/" + assetBundleName;        UnityEngine.Networking.UnityWebRequest request = UnityEngine.Networking.UnityWebRequest.GetAssetBundle(uri, 0);
        yield return request.Send();
        AssetBundle bundle = DownloadHandlerAssetBundle.GetContent(request);
        GameObject cube = bundle.LoadAsset("Cube");
        GameObject sprite = bundle.LoadAsset("Sprite");
        Instantiate(cube);
        Instantiate(sprite);
    }

boundle加载就完成了，但是在实际工程中，boundle不可能这么简单，我们在实际工程中应用的时候，需要具体问题具体分析。
我们要加载AssetBundleManifest时候 ，用以下代码就可以，先加载boundle，然后加载Manifest文件，分析相关的依赖项。

加载AssetBundle Manifests

AssetBundle assetBundle = AssetBundle.LoadFromFile(manifestFilePath);
AssetBundleManifest manifest = assetBundle.LoadAsset("AssetBundleManifest");