samples/cupertino_gallery/lib/settings_page.dart

import 'package:flutter/cupertino.dart';

class SettingsPage extends StatefulWidget {
  const SettingsPage({
    super.key,
    required this.onThemeChange,
    required this.isDarkMode,
    required this.onTextSizeChange,
    required this.textSize,
  });

  final ValueChanged<bool> onThemeChange;
  final bool isDarkMode;
  final ValueChanged<double> onTextSizeChange;
  final double textSize;

  @override
  State<SettingsPage> createState() => _SettingsPageState();
}

class _SettingsPageState extends State<SettingsPage> {
  late bool isDarkMode;
  late double _textSize;

  @override
  void initState() {
    super.initState();
    isDarkMode = widget.isDarkMode;
    _textSize = widget.textSize;
  }

  @override
  void didUpdateWidget(SettingsPage oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.isDarkMode != oldWidget.isDarkMode) {
      isDarkMode = widget.isDarkMode;
    }
    if (widget.textSize != oldWidget.textSize) {
      _textSize = widget.textSize;
    }
  }

  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      navigationBar: const CupertinoNavigationBar(middle: Text('Settings')),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          CupertinoListSection(
            header: const Text('Appearance'),
            children: [
              CupertinoListTile(
                title: const Text('Dark Mode'),
                trailing: CupertinoSwitch(
                  value: isDarkMode,
                  onChanged: (isActive) {
                    setState(() {
                      isDarkMode = isActive;
                      widget.onThemeChange(isActive);
                    });
                  },
                ),
              ),
              CupertinoListTile(
                title: const Text('Text Size'),
                trailing: Text('${(_textSize * 100).toStringAsFixed(0)}%'),
              ),
              CupertinoSlider(
                value: _textSize,
                min: 0.5,
                max: 1.5,
                onChanged: (value) {
                  setState(() {
                    _textSize = value;
                  });
                  widget.onTextSizeChange(value);
                },
              ),
            ],
          ),
          CupertinoListSection(
            header: const Text('General'),
            children: [
              CupertinoListTile(
                title: const Text('About'),
                trailing: const Icon(CupertinoIcons.forward),
                onTap: () {},
              ),
              CupertinoListTile(
                title: const Text('Privacy'),
                trailing: const Icon(CupertinoIcons.forward),
                onTap: () {},
              ),
              CupertinoListTile(
                title: const Text('Help'),
                trailing: const Icon(CupertinoIcons.forward),
                onTap: () {},
              ),
              CupertinoListTile(
                title: const Text('Reset Settings'),
                trailing: const Icon(CupertinoIcons.forward),
                onTap: () {
                  showCupertinoDialog<void>(
                    context: context,
                    builder: (context) => CupertinoAlertDialog(
                      title: const Text('Reset Settings'),
                      content: const Text(
                        'Are you sure you want to reset all settings?',
                      ),
                      actions: <CupertinoDialogAction>[
                        CupertinoDialogAction(
                          child: const Text('Cancel'),
                          onPressed: () {
                            Navigator.pop(context);
                          },
                        ),
                        CupertinoDialogAction(
                          isDestructiveAction: true,
                          child: const Text('Reset'),
                          onPressed: () {
                            setState(() {
                              isDarkMode = false;
                              _textSize = 1.0;
                              widget.onThemeChange(false);
                              widget.onTextSizeChange(1.0);
                            });
                            Navigator.pop(context);
                          },
                        ),
                      ],
                    ),
                  );
                },
              ),
            ],
          ),
        ],
      ),
    );
  }
}