CupertinoPicker class

This example shows a CupertinoPicker that displays a list of fruits on a wheel for selection.

import 'package:cupertino_ui/cupertino_ui.dart';

/// Flutter code sample for [CupertinoPicker].

const double _kItemExtent = 32.0;
const List<String> _fruitNames = <String>[
  'Apple',
  'Mango',
  'Banana',
  'Orange',
  'Pineapple',
  'Strawberry',
];

void main() => runApp(const CupertinoPickerApp());

class CupertinoPickerApp extends StatelessWidget {
  const CupertinoPickerApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const CupertinoApp(
      theme: CupertinoThemeData(brightness: .light),
      home: CupertinoPickerExample(),
    );
  }
}

class CupertinoPickerExample extends StatefulWidget {
  const CupertinoPickerExample({super.key});

  @override
  State<CupertinoPickerExample> createState() => _CupertinoPickerExampleState();
}

class _CupertinoPickerExampleState extends State<CupertinoPickerExample> {
  int _selectedFruit = 0;

  // This shows a CupertinoModalPopup with a reasonable fixed height which hosts CupertinoPicker.
  void _showDialog(Widget child) {
    showCupertinoModalPopup<void>(
      context: context,
      builder: (BuildContext context) => Container(
        height: 216,
        padding: const .only(top: 6.0),
        // The Bottom margin is provided to align the popup above the system navigation bar.
        margin: .only(bottom: MediaQuery.of(context).viewInsets.bottom),
        // Provide a background color for the popup.
        color: CupertinoColors.systemBackground.resolveFrom(context),
        // Use a SafeArea widget to avoid system overlaps.
        child: SafeArea(top: false, child: child),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: const CupertinoNavigationBar(
        middle: Text('CupertinoPicker Sample'),
      ),
      child: DefaultTextStyle(
        style: TextStyle(
          color: CupertinoColors.label.resolveFrom(context),
          fontSize: 22.0,
        ),
        child: Center(
          child: Row(
            mainAxisAlignment: .center,
            children: <Widget>[
              const Text('Selected fruit: '),
              CupertinoButton(
                padding: .zero,
                // Display a CupertinoPicker with list of fruits.
                onPressed: () => _showDialog(
                  CupertinoPicker(
                    magnification: 1.22,
                    squeeze: 1.2,
                    useMagnifier: true,
                    itemExtent: _kItemExtent,
                    // This sets the initial item.
                    scrollController: FixedExtentScrollController(
                      initialItem: _selectedFruit,
                    ),
                    // This is called when selected item is changed.
                    onSelectedItemChanged: (int selectedItem) {
                      setState(() {
                        _selectedFruit = selectedItem;
                      });
                    },
                    children: [
                      for (final String fruitName in _fruitNames)
                        Center(child: Text(fruitName)),
                    ],
                  ),
                ),
                // This displays the selected fruit name.
                child: Text(
                  _fruitNames[_selectedFruit],
                  style: const TextStyle(fontSize: 22.0),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}