How to implement a SliverAppBar with a collapsable search bar - flutter

Question

This is what I'm trying to do, it's a pretty common Widget on iOS. This is my code:
return Scaffold(
backgroundColor: Colors.white,
body: CustomScrollView(
slivers: <Widget>[
SliverAppBar(
automaticallyImplyLeading: false,
pinned: true,
titleSpacing: 0,
backgroundColor: Colors.white,
elevation: 1.0,
title: Container(
width: double.infinity,
child: Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.spaceAround,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
CupertinoButton(
padding: EdgeInsets.all(0),
onPressed: () {},
child: AutoSizeText(
'Ordenar',
style: TextStyle(
color: Color(0xff16161F),
fontFamily: 'Brutal',
fontSize: 17.0,
),
),
),
AutoSizeText(
'Equipos 14',
style: TextStyle(
color: Color(0xff16161F),
fontFamily: 'Archia',
fontSize: 22.0,
),
),
CupertinoButton(
padding: EdgeInsets.all(0),
onPressed: () {},
child: AutoSizeText(
'Editar',
style: TextStyle(
color: Color(0xff16161F),
fontFamily: 'Brutal',
fontSize: 17.0,
),
),
),
],
),
),
centerTitle: true,
),
SliverFillRemaining(
child: Center(
child: CupertinoButton(
onPressed: () {
setState(() {
(isBottom) ? isBottom = false : isBottom = true;
});
},
child: Text('YESSS'),
),
),
),
],
),
bottomNavigationBar: (isBottom) ? _toolBar() : _tabBar(),
);
I've tried adding a CupertinoTextField() to the bottom property, but it gets into my Row() and messes up everything. Has anyone done this, or knows how to achieve it?
Thanks.

Answer 1

I managed to solve it. SliverAppBar has a property called flexibleSpace. In here you put a FlexibleSpaceBar, which contains a background property. Now, don't be fooled, this is not limited to a solid color or an image. It can take any Widget you want. In my case, I wanted to add a search bar. And because this property will fill the entire expandedHeight property, you want to add a small blank space so your custom widgets don't get drawn over your SliverAppBar. Here's the relevant piece of code:
flexibleSpace: FlexibleSpaceBar(
background: Column(
children: <Widget>[
SizedBox(height: 90.0),
Padding(
padding: const EdgeInsets.fromLTRB(16.0, 6.0, 16.0, 16.0),
child: Container(
height: 36.0,
width: double.infinity,
child: CupertinoTextField(
keyboardType: TextInputType.text,
placeholder: 'Filtrar por nombre o nombre corto',
placeholderStyle: TextStyle(
color: Color(0xffC4C6CC),
fontSize: 14.0,
fontFamily: 'Brutal',
),
prefix: Padding(
padding:
const EdgeInsets.fromLTRB(9.0, 6.0, 9.0, 6.0),
child: Icon(
Icons.search,
color: Color(0xffC4C6CC),
),
),
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(8.0),
color: Color(0xffF0F1F5),
),
),
),
),
],
),
),
),
And here is the result. The search bar will disappear when the scroll goes up. Hope this helps anyone wanting to do this.