Flutter: Keep BottomNavigationBar When Push to New Screen with Navigator

Question

In iOS, we have a UITabBarController which stays permanently at the bottom of the screen when we push to a new ViewController.

In Flutter, we have a bottomNavigation

Answer 1

You can use Nested Routes of auto_route package, that's how I implemented it. Here is the link if anyone wants for reference auto_route

One other way you can implement this is by using get package.

Nested routes are not recommended as they can create the memory leak in some cases.

Answer 2

I created a small, super easy to use package that let you do that effect CustomNavigator And wrote a tutorial about it on Medium you can find it here

Answer 3

Another way to achieve this (though not good practice) is to nest a material app in the body of your scaffold. And handle all "sub-navigation" there.

So, your hierarchy will look like this

Material App
  - home
     - Scaffold
       - body
         - Material App
              - Scaffold
                  - AppBar
                  - body
                  ...
         - routes (internal)
       - bottomNavigationBar
  - routes (external)

I've tried this and it works perfectly. Unfortunately I can't post the source code now.

Answer 4

You could actually place a placeholder inside body so the structure like this

- AppBar
- body (dynamic content from placeholder)
- BottomNavigationBar

Then you would have another class as a placeholder So each time you tap on the BottomNavigationBar it will refresh content of the body

One example I found is here https://willowtreeapps.com/ideas/how-to-use-flutter-to-build-an-app-with-bottom-navigation

and here but a litte too complex and not working for me https://medium.com/@swav.kulinski/flutter-navigating-off-the-charts-e118562a36a5

and this https://medium.com/coding-with-flutter/flutter-case-study-multiple-navigators-with-bottomnavigationbar-90eb6caa6dbf

Answer 5

I think the #right way of doing this would be to have the BottomNavigationBar wrapped in a Hero in both cases with the same tag. This way, when the animation between pages happens they would be excluded.

This is as brief as an example as I could make, but I'd highly recommend cleaning it up i.e. passing the hero string in, using widgets rather than a huge block of build, making your own widget for BottomNavigationBar.

Note that during the hero transition it does overflow by 0.0000191 pixels on my phone at least, but in release mode that shouldn't be an issue I don't think.

import 'package:flutter/material.dart';

void main() => runApp(new MaterialApp(
      home: new Builder(
        builder: (context) => new Scaffold(
              bottomNavigationBar: new Hero(
                tag: "bottomNavigationBar",
                child: new BottomNavigationBar(items: [
                  new BottomNavigationBarItem(icon: new Icon(Icons.home), title: new Text("Home")),
                  new BottomNavigationBarItem(icon: new Icon(Icons.ac_unit), title: new Text("AC Unit"))
                ]),
              ),
              body: new SafeArea(
                child: new Container(
                  constraints: new BoxConstraints.expand(),
                  color: Colors.green,
                  child: new Column(
                    children: <Widget>[
                      new RaisedButton(
                          child: new Text("Press me"),
                          onPressed: () {
                            Navigator.push(
                                context,
                                new MaterialPageRoute(
                                    builder: (context) => new Scaffold(
                                          bottomNavigationBar: new Hero(
                                            tag: "bottomNavigationBar",
                                            child: new BottomNavigationBar(items: [
                                              new BottomNavigationBarItem(icon: new Icon(Icons.home), title: new Text("Home")),
                                              new BottomNavigationBarItem(icon: new Icon(Icons.ac_unit), title: new Text("AC Unit"))
                                            ]),
                                          ),
                                          body: new SafeArea(
                                            child: new Container(
                                              constraints:
                                                  new BoxConstraints.expand(),
                                              color: Colors.red,
                                              child: new Column(
                                                children: <Widget>[
                                                  new RaisedButton(
                                                    onPressed: () =>
                                                        Navigator.pop(context),
                                                    child: new Text("Back"),
                                                  )
                                                ],
                                              ),
                                            ),
                                          ),
                                        )));
                          })
                    ],
                  ),
                ),
              ),
            ),
      ),
    ));

I don't know how well the hero system handles multiple heroes etc, and if you say wanted to animate the navigation bar this might not work overly well.

There is another way of doing this which would allow you to animate the bottom navigation bar; it's actually a question that has already been answered though: Flutter: Hero transition + widget animation at the same time?

Answer 6

You can create Navigator widget in a Stack widget to use BottomNavigationBar with tabs' inner navigation. You can use WillPopScope to handle Android's back button to pop inner screens of tab. Also, double tap bottom navigation item to pop all inner screens of a tab.

I've created a Sample app for this.

Hope this help!