class _myBottomSheetState extends State<myBottomSheet> {
  double appbarSize=0.08;
  @override
  Widget build(BuildContext context) {
    return DraggableScrollableSheet(
      maxChildSize: 0.8,
      minChildSize: appbarSize,
      initialChildSize: appbarSize,
      builder: (BuildContext context, ScrollController scrollController) {
        _scrollListener(){
         //use controller such in the guide
        }

        scrollController.addListener(_scrollListener); // <----------------
        return Container(
          child: ListView.builder(
            controller: scrollController,
            itemCount: 25,
            itemBuilder: (BuildContext context, int index) {
              return ListTile(title: Text('Item $index'));
            },
          ),
        );
      },
    );
  }