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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return CupertinoPageScaffold(
      child: Center(
        child: CupertinoButton(
          child: Text('Alert'),
          onPressed: () {
            showDialog<void>(
                context: context,
                builder: (BuildContext context) {
                  return CupertinoAlertDialog(
                    title: Text('Title'),
                    content: Text('Content'),
                    actions: <Widget>[
                      CupertinoDialogAction(
                        child: Text('Cancel'),
                        onPressed: () => Navigator.of(context).pop(),
                      ),
                      CupertinoDialogAction(
                        child: Text('Ok'),
                        onPressed: () => Navigator.of(context).pop(),
                        isDefaultAction: true,
                      ),
                    ],
                  );
                });
          },
        ),
      ),
    );
  }
}