在项目列表中，将类型设置为data to add checkbox或sep以添加标题。对话框的输出将是{2，3}形式的字典，其中value 2 = Cordoba。

完整代码

import 'package:flutter/material.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomeScreen(),
    );
  }
}

class MultiSelectDialogItem<V> {
  V value;

  String name;
  String type;

  MultiSelectDialogItem(
      {required this.name, required this.type, required this.value});
}

class MultiSelectDialog<V> extends StatefulWidget {
  const MultiSelectDialog({
    Key? key,
    required this.items,
    required this.initialSelectedValues,
  }) : super(key: key);

  final List<MultiSelectDialogItem<V>> items;
  final Set<V> initialSelectedValues;

  @override
  State<StatefulWidget> createState() => _MultiSelectDialogState<V>();
}

class _MultiSelectDialogState<V> extends State<MultiSelectDialog<V>> {
  final _selectedValues = <V>{};

  @override
  void initState() {
    super.initState();
    _selectedValues.addAll(widget.initialSelectedValues);
  }

  void _onItemCheckedChange(V itemValue, bool checked) {
    setState(() {
      if (checked) {
        _selectedValues.add(itemValue);
      } else {
        _selectedValues.remove(itemValue);
      }
    });
  }

  void _onCancelTap() {
    Navigator.pop(context);
  }

  void _onSubmitTap() {
    Navigator.pop(context, _selectedValues);
  }

  @override
  Widget build(BuildContext context) {
    return AlertDialog(
      title: const Text('Select place'),
      contentPadding: const EdgeInsets.all(20.0),
      content: SingleChildScrollView(
        child: ListTileTheme(
          contentPadding: const EdgeInsets.fromLTRB(14.0, 0.0, 24.0, 0.0),
          child: ListBody(
            children: widget.items.map(_buildItem).toList(),
          ),
        ),
      ),
      actions: <Widget>[
        ElevatedButton(
          onPressed: _onCancelTap,
          child: const Text('CANCEL'),
        ),
        ElevatedButton(
          onPressed: _onSubmitTap,
          child: const Text('OK'),
        )
      ],
    );
  }

  Widget _buildItem(MultiSelectDialogItem<V> item) {
    final checked = _selectedValues.contains(item.value);
    return item.type == "data"
        ? CheckboxListTile(
            value: checked,
            title: Text(item.name),
            controlAffinity: ListTileControlAffinity.leading,
            onChanged: (checked) => _onItemCheckedChange(item.value, checked!),
          )
        : Container(
            child: Padding(
              padding: const EdgeInsets.all(10.0),
              child: Text(
                item.name,
                style: TextStyle(color: Color.fromARGB(255, 91, 91, 91)),
              ),
            ),
          );
  }
}

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

  @override
  HomeScreenState createState() => HomeScreenState();
}

class HomeScreenState extends State<HomeScreen> {
  void _showMultiSelect(BuildContext context) async {
    final items = <MultiSelectDialogItem<int>>[
      MultiSelectDialogItem(name: 'Argentina', type: 'sep', value: 1),
      MultiSelectDialogItem(name: 'Cordoba', type: 'data', value: 2),
      MultiSelectDialogItem(name: 'Chaco', type: 'data', value: 3),
      MultiSelectDialogItem(name: 'Buenos Aires', type: 'data', value: 4),
      MultiSelectDialogItem(name: 'USA', type: 'sep', value: 5),
      MultiSelectDialogItem(name: 'California', type: 'data', value: 6),
      MultiSelectDialogItem(name: 'Florida', type: 'data', value: 7),
    ];

    final selectedValues = await showDialog<Set>(
      context: context,
      builder: (BuildContext context) {
        return MultiSelectDialog(
          items: items,
          initialSelectedValues: [].toSet(),
        );
      },
    );

    print(selectedValues);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          child: Text("show dialog"),
          onPressed: () {
            _showMultiSelect(context);
          },
        ),
      ),
    );
  }
}

输出

希望这对你有帮助。快乐编码：）