Flutter:日期选择器切换到输入模式？

DateTime selectedDate = DateTime.now();

Future<void> _selectDate(BuildContext context) async {
  final DateTime? picked = await showDatePicker(
    context: context,
    initialDate: selectedDate,
    firstDate: DateTime(2015),
    lastDate: DateTime(2022),
    builder: (BuildContext context, Widget? child) {
      return Theme(
        data: ThemeData.light(), // 设置主题样式
        child: child!,
      );
    },
  );

  if (picked != null && picked != selectedDate) {
    setState(() {
      selectedDate = picked;
    });
  }
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: const Text('Flutter日期选择器切换到输入模式'),
    ),
    body: Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: <Widget>[
          Text('选择的日期: ${selectedDate.toString()}'),
          ElevatedButton(
            onPressed: () => _selectDate(context),
            child: const Text('选择日期'),
          ),
        ],
      ),
    ),
  );
}