Flutter: Persistent BottomAppBar and BottomNavigationBar - flutter

Question

I am new to flutter, and I am building an app that has BottomAppBar which takes the property bottomNavigationBar: of Scaffold() for my home_screen, because I needed it to be at the bottom of the screen and persistent throughout the pages, and I also need a BottomNavigationBar to be persistent also at the top of BottomAppBar, but I can't make that happen because BottomAppBar already takes the bottomNavigationBar: property.
How can I make my BottomNavigationBar persistent alongside my BottomAppBar?
Note: I am using PageView() to scroll through my pages and it will be controlled by the BottomNavigationBar
Edit: attached here is the UI that I am trying to achieve
code snippet:
import 'package:flutter/material.dart';
//screens
import 'package:timewise_flutter/screens/calendar_screen.dart';
import 'package:timewise_flutter/screens/covey_quadrants_screen.dart';
import 'package:timewise_flutter/screens/kanban_screen.dart';
import 'package:timewise_flutter/screens/todo_list_screen.dart';
class OverviewScreen extends StatefulWidget {
static const String id = 'overview_screen';
//const OverviewScreen({Key? key}) : super(key: key);
#override
_OverviewScreenState createState() => _OverviewScreenState();
}
class _OverviewScreenState extends State<OverviewScreen> {
PageController _pageController = PageController(initialPage: 2);
int _bottomNavBarCurrentIndex = 2;
#override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
bottomNavigationBar: SafeArea(
child: BottomAppBar(
elevation: 16.0,
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
IconButton(
tooltip: 'Menu',
icon: Icon(Icons.menu_rounded),
onPressed: () {
print('menu icon pressed!');
//TODO: show bottom modal bottom sheet
},
),
IconButton(
tooltip: 'Pomodoro Timer',
icon: Icon(Icons.hourglass_empty_rounded),
onPressed: () {
print('pomo icon pressed!');
//TODO: show pomodoro timer modal bottom sheet
},
),
IconButton(
tooltip: 'Add',
icon: Icon(Icons.add_circle_outline_outlined),
onPressed: () {
print('add icon pressed!');
//TODO: show add task modal bottom sheet
},
),
],
),
);,
),
body: PageView(
controller: _pageController,
onPageChanged: (page) {
setState(() {
_bottomNavBarCurrentIndex = page;
});
},
children: [
CalendarScreen(),
ToDoListScreen(),
SafeArea(
child: Container(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Text('Overview Screen'),
BottomNavigationBar(
currentIndex: _bottomNavBarCurrentIndex,
type: BottomNavigationBarType.fixed,
backgroundColor: Colors.white,
elevation: 0.0,
iconSize: 16.0,
selectedItemColor: Colors.black,
unselectedItemColor: Colors.grey,
showSelectedLabels: false,
showUnselectedLabels: false,
items: [
BottomNavigationBarItem(
icon: Icon(Icons.calendar_today_rounded),
label: 'Calendar',
tooltip: 'Calendar',
),
BottomNavigationBarItem(
icon: Icon(Icons.checklist_rounded),
label: 'To-Do',
tooltip: 'To-Do List',
),
BottomNavigationBarItem(
icon: Icon(Icons.panorama_fish_eye_rounded),
label: 'Overview',
tooltip: 'Overview',
),
BottomNavigationBarItem(
icon: Icon(Icons.border_all_rounded),
label: 'Covey\'s 4 Quadrants',
tooltip: 'Covey\'s 4 Quadrants',
),
BottomNavigationBarItem(
icon: Icon(Icons.view_column_rounded),
label: 'Kanban Board',
tooltip: 'Kanban Board',
),
],
onTap: (index) {
setState(() {
_bottomNavBarCurrentIndex = index;
_pageController.jumpToPage(index);
});
},
),
],
),
),
),
CoveyQuadrantsScreen(),
KanbanScreen(),
],
),
);
}
}

Answer 1

Unfortunately, this is not a standard way in which the mobile app UI should be designed. This will result in bad user experience.
What if user accidently touches on NavigationBar instead of
AppBar. You will be taken to the new screen and action that I
performed there will be lost or need to handle.
So proper UI guidelines should be met, while we design and develop for the mobile app. Based on guidelines from material.io
Bottom app bars should be used for:
Mobile devices only
Access to a bottom navigation drawer
Screens with two to five actions
Bottom app bars shouldn't be used for:
Apps with a bottom navigation bar
Screens with one or no actions
Refer this link for more useful information about the UI and UX guidelines https://material.io/

Answer 2

I would suggest making a scaffold() with the bottomNavigationBar() as you did. Then you could create a list of Container() objects each representing a different page. For your PageView I'm assuming you have done that, if not then that's the way to do it. Then you could cycle through your pages by setting the body: property of the scaffold to myPages[_currentIndex] or something like that.
Additionally: Like the comment asks, I am also not sure why you would want both BottomNavigationBar and BottomAppBar they both do exactly the same thing. In either case the process is the same as what I described above.