c#dalegate invoke及AsyncCallback使用

        public delegate void AsyncDelegate();
        private AsyncDelegate asyncDl;

                  asyncDl = new AsyncDelegate(() =>
                {
                   //todo
                });

                AsyncCallback callBack = new AsyncCallback((s) =>
                {

                         //todo
                });

              asyncDl.BeginInvoke(callBack, null); //启动执行

            当异步方法执行完毕会调用callBack方法