Permanent Persistent Bottom sheet flutter

Also you can use WillPopScope Widget to control pressing back button:

Widget _buildBottomSheet() {
    return WillPopScope(
        onWillPop: () {
            **here you can handle back button pressing. Just leave it empty to disable back button**
        },
        child: **your bottom sheet**
        )),
    );
}

Scaffold now has a bottom sheet argument and this bottom sheet cannot be dismissed by swiping down the screen.

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(....),
        bottomSheet: Container(
            child: Text('Hello World'),
        ),
    );
  }