FlutterBottomAppBar

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      floatingActionButton: FloatingActionButton(
        backgroundColor: Colors.black,
        child: const Icon(Icons.add),
        onPressed: () {},
      ),
      bottomNavigationBar: new BottomAppBar(
        hasNotch: true,
        color: Colors.indigo,
        child: new Row(
          mainAxisSize: MainAxisSize.max,
          children: <Widget>[
            IconButton(
              icon: Icon(
                Icons.menu,
                color: Colors.white,
              ),
              onPressed: () {},
            ),
            new Expanded(child: new SizedBox()),
            IconButton(
              icon: Icon(
                Icons.search,
                color: Colors.white,
              ),
              onPressed: () {},
            ),
            IconButton(
              icon: Icon(
                Icons.more_vert,
                color: Colors.white,
              ),
              onPressed: () {},
            ),
          ],
        ),
      ),
    );
  }
}