我想在flutter中显示自定义进度对话框(类似于iOS默认对话框

dependencies:
  progress_dialog: ^1.2.4

import 'package:flutter/material.dart';
import 'package:progress_dialog/progress_dialog.dart';

void showCustomProgressDialog(BuildContext context) async {
  final ProgressDialog progressDialog = ProgressDialog(context,
      type: ProgressDialogType.Download, isDismissible: false);
  progressDialog.style(
      message: '加载中...',
      borderRadius: 10.0,
      backgroundColor: Colors.white,
      progressWidget: CircularProgressIndicator(),
      elevation: 10.0,
      insetAnimCurve: Curves.easeInOut,
      progress: 0.0,
      maxProgress: 100.0,
      progressTextStyle:
          TextStyle(color: Colors.black, fontSize: 13.0, fontWeight: FontWeight.w400),
      messageTextStyle:
          TextStyle(color: Colors.black, fontSize: 19.0, fontWeight: FontWeight.w600));
  progressDialog.show();
  
  // 模拟一个耗时操作，比如网络请求
  await Future.delayed(Duration(seconds: 2));
  
  progressDialog.update(
    progress: 50.0,
    message: "加载中，请稍候...",
    progressWidget: CircularProgressIndicator(value: 0.5),
    maxProgress: 100.0,
    progressTextStyle:
        TextStyle(color: Colors.black, fontSize: 13.0, fontWeight: FontWeight.w400),
    messageTextStyle:
        TextStyle(color: Colors.black, fontSize: 19.0, fontWeight: FontWeight.w600),
  );
  
  await Future.delayed(Duration(seconds: 2));
  
  progressDialog.hide();
}

FlatButton(
  onPressed: () {
    showCustomProgressDialog(context);
  },
  child: Text('显示自定义进度对话框'),
)