（6）AB包资源管理器-异步加载

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ABAsyncTest : MonoBehaviour
{
    void Start()
    {
        //第一种
        ABMgr.GetInstance().LoadResAsync("model", "Cube", (obj) =>
        {
            (obj as GameObject).transform.position = -Vector3.up;
        });
        //第二种（Type方式）
        ABMgr.GetInstance().LoadResAsync("model", "Cube",typeof(GameObject), (obj) =>
        {
            (obj as GameObject).transform.position = -Vector3.up;
        });
        //第三种（泛型方式）
        ABMgr.GetInstance().LoadResAsync<GameObject>("model", "Cube", (obj) =>
        {
            obj.transform.position = -Vector3.up;
        });
    }
}

using System.Collections.Generic;
using UnityEngine;
/// <summary>
/// 知识点
/// 1.AB包先关的API
/// 2.单例模式
/// 3.委托 -> Lambda表达式
/// 4.协程
/// 5.字典
/// </summary>
public class ABMgr : SingletonAutoMono<ABMgr>
{
    //AB包管理器 目的是：让外部更方便的进行资源加载
    //主包
    private AssetBundle mainAB = null;
    //依赖包获取用的配置文件
    private AssetBundleManifest manifest = null;
    /// <summary>
    /// AB包存放路径 方便修改
    /// </summary>
    private string pathUrl
    {
        get
        {
            return Application.streamingAssetsPath + "/";
        }
    }
    /// <summary>
    /// 主包名 方便修改
    /// </summary>
    private string MainABName
    {
        get
        {
#if UNITY_IOS
                return "IOS";
#elif UNITY_ANDROID
                return "Android";
#else
            return "PC";
        }
    }
    //AB包不能够重复加载 重复加载会报错
    //字典 用字典来存储 加载过的AB包
    private Dictionary<string, AssetBundle> abDic = new Dictionary<string, AssetBundle>();//存储AB包容器
    /// <summary>
    /// 加载AB包
    /// </summary>
    /// <param name="abName"></param>
    private void LoadAB(string abName)
    {
        //加载AB包
        if (mainAB == null)
        {
            mainAB = AssetBundle.LoadFromFile(pathUrl + "PC");
            manifest = mainAB.LoadAsset<AssetBundleManifest>("AssetBundleManifest");//得到主包的配置文件
        }
        //获取依赖包相关信息
        AssetBundle ab;
        string[] strs = manifest.GetAllDependencies(abName);//通过配置文件得到相关依赖包
        for (int i = 0; i < strs.Length; i++)
        {
            //判断包是否加载过
            if (abDic.ContainsKey(strs[i]))
            {
                ab = AssetBundle.LoadFromFile(pathUrl + strs[i]);
                abDic.Add(strs[i], ab);
            }
        }
        //加载资源来源包(如果没有加载过，再加载)
        if (!abDic.ContainsKey(abName))
        {
            ab = AssetBundle.LoadFromFile(pathUrl + abName);
        }
    }
    //异步加载的方法
    //这里的异步加载 AB包并没有使用异步加载
    //知识从AB包中 加载资源时 使用异步
    /// <summary>
    /// 根据名字异步加载资源
    /// </summary>
    /// <param name="abName"></param>
    /// <param name="resName"></param>
    /// <param name="callBack"></param>
    private void LoadResAsync(string abName, string resName,UnityAction<Object> callBack)//提供给外部方法，用于启动协程
    {
        StartCoroutine(ReallyLoadResAsync(abName,resName,callBack));
    }
    private IEnumerator ReallyLoadResAsync(string abName,string resName,UnityAction<Object> callBack)//正儿八经要用到的协程
    {
        AssetBundleRequest abr = abDic[abName].LoadAssetAsync(resName);
        //异步加载结束后 通过委托 传递给外部 外部来使用
        if(abr.asset == null )
        if (abr.asset is GameObject)
        {
            callBack(Instantiate(abr.asset));
        }
        else callBack(abr.asset);
        yield return null;
    }
    /// <summary>
    /// 根据Type异步加载资源
    /// </summary>
    /// <param name="abName"></param>
    private void LoadResAsync(string abName, string resName, System.Type type,UnityAction<Object> callBack)//提供给外部方法，用于启动协程
    {
        StartCoroutine(ReallyLoadResAsync(abName, resName, callBack));
    }
    private IEnumerator ReallyLoadResAsync(string abName, string resName, System.Type type, UnityAction<Object> callBack)//正儿八经要用到的协程
    {
        AssetBundleRequest abr = abDic[abName].LoadAssetAsync(resName,type);
        //异步加载结束后 通过委托 传递给外部 外部来使用
        if (abr.asset == null)
            if (abr.asset is GameObject)
            {
                callBack(Instantiate(abr.asset));
            }
            else callBack(abr.asset);
        yield return null;
    }
    /// <summary>
    /// 根据泛型异步加载
    /// </summary>
    /// <param name="abName"></param>
    private void LoadResAsync<T>(string abName, string resName, UnityAction<T> callBack) where T:Object//提供给外部方法，用于启动协程
    {
        StartCoroutine(ReallyLoadResAsync<T>(abName, resName, callBack));
    }
    private IEnumerator ReallyLoadResAsync<T>(string abName, string resName, UnityAction<T> callBack)//正儿八经要用到的协程
    {
        AssetBundleRequest abr = abDic[abName].LoadAssetAsync(resName);
        //异步加载结束后 通过委托 传递给外部 外部来使用
        if (abr.asset == null)
            if (abr.asset is GameObject)
            {
                callBack(Instantiate(abr.asset) as T);
            }
            else callBack(abr.asset);
        yield return null;
    }
    //单个包卸载
    public void UnLoad(string abName)
    {
        if (abDic.ContainsKey(abName))
        {
            abDic[abName].Unload(false);
            abDic.Remove(abName);
        }
    }
    //所有包的卸载
    public void ClearAB()
    {
        AssetBundle.UnloadAllAssetBundles(false);
        abDic.Clear();
        mainAB = null;
        manifest = null;
    }
}