How to call CupertinoPicker - flutter

Question

I would like to show CupertinoPicker, when some button is pressed.
However I have no idea where I should implement CupertinoPicker.
Following code is sample of code which I don't know where I write to call.
showCupertinoModalPopup<String>(
context: context,
builder:(BuildContext context){
return _buildBottomPicker(CupertinoPicker(
onSelectedItemChanged: (value){
setState((){
selectedValue = value;
});
},
itemExtent: 32.0,
children: const[
Text('Item01'),
Text('Item02'),
Text('Item03'),
],
));
},
);

Answer 1

Here is the complete workable demo for launching cupertino picker when a button is pressed. Hope this solves your query.
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: WeightSelect(),
debugShowCheckedModeBanner: false,
);
}
}
class WeightSelect extends StatefulWidget {
#override
_WeightSelectState createState() => _WeightSelectState();
}
class _WeightSelectState extends State<WeightSelect> {
int selectedValue;
showPicker() {
showModalBottomSheet(
context: context,
builder: (BuildContext context) {
return CupertinoPicker(
backgroundColor: Colors.white,
onSelectedItemChanged: (value) {
setState(() {
selectedValue = value;
});
},
itemExtent: 32.0,
children: const [
Text('Item01'),
Text('Item02'),
Text('Item03'),
],
);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Cupertino picker demo"),
),
body: Column(
children: <Widget>[
const SizedBox(height: 10.0),
Text("Selected: $selectedValue"),
const SizedBox(height: 10.0),
Center(
child: RaisedButton(
onPressed: showPicker,
child: Text("Show picker"),
),
),
],
),
);
}
}

Answer 2

It should be written when you want to open a popup or alertdialog with iOS cupertino style.
You can view the demo here :
http://flutterdevs.com/blog/know-your-widgets-1-cupertino-ios-style-actionsheet-in-flutter/
It may be displayed on button click when you need some confirmation or direction from the user.