1.创建C#类库(dll)项目

2.删除命名空间，不然可能会出错

public class Manager
{
    private int count;

    public Manager()
    {
        count = 2;
    }

    public string IntToStr()
    {
        return count.ToString();
    }

}

public class Login:MonoBehaviour
{
    void Start()
    {
        Manager mgr = new Manager();
        Debug.Log(mgr.IntToStr());
    }
}

3.点击生成

将Test2.dll 的后缀名改为bytes ->  Test2.bytes

将这个文件拖拽到Unity工程中

将工程打包为Hot.unitypackage

本次样例路径：C:/Users/14486/Desktop/2020/热更新学习/Hot/Hot.unitypackage

在unity项目中添加脚本：

    private static readonly string DLL_URL = "file:///C:/Users/14486/Desktop/2020/热更新学习/Hot/Hot.unitypackage";
    void Start()
    {
        StartCoroutine(LoadDllScript());
    }

    private IEnumerator LoadDllScript()
    {        
        WWW www = new WWW(DLL_URL);        
        yield return www;
        
        AssetBundle bundle = www.assetBundle;
        if (bundle == null)
            Debug.Log("Is NUll");
        TextAsset asset = bundle.LoadAsset("Test2", typeof(TextAsset)) as TextAsset;

        System.Reflection.Assembly assembly = System.Reflection.Assembly.Load(asset.bytes);
        System.Type login = assembly.GetType("Login");
        GameObject obj = new GameObject();
        obj.AddComponent(login);
    }

运行即可