pull_ to_ refresh

dependencies:
 pull_to_refresh: ^1.5.7

class _MyHomePageState extends State<MyHomePage> {
 List<String> items = ["1", "2", "3", "4", "5", "6", "7", "8"];
 RefreshController _refreshController =
 RefreshController(initialRefresh: false);

 void _onRefresh() async {
  // monitor network fetch
  await Future.delayed(Duration(milliseconds: 1000));
  // if failed,use refreshFailed()
  _refreshController.refreshCompleted();
 }

 void _onLoading() async {
  // monitor network fetch
  await Future.delayed(Duration(milliseconds: 1000));
  // if failed,use loadFailed(),if no data return,use LoadNodata()
  items.add((items.length + 1).toString());
  if (mounted) setState(() {});
  _refreshController.loadComplete();
 }

 @override
 Widget build(BuildContext context) {
  return Scaffold(
   body: SmartRefresher(
    enablePullDown: true,
    ena