title: Recommended Dark/Light or custom Theme implementation in Flutter Cupertino
body: <p>I’m currently implementing an iOS style app in flutter using the <a href="https://docs.flutter.io/flutter/cupertino/CupertinoApp-class.html" rel="noreferrer">CupertinoApp class</a> and <a href="https://flutter.io/docs/development/ui/widgets/cupertino" rel="noreferrer">Cupertino widgets</a>. Now I would like to implement a different Theme for the application (like <a href="https://itunes.apple.com/de/app/feedly-smart-news-reader/id396069556?mt=8" rel="noreferrer">feedly</a> did), so that the user can switch between both during runtime.</p>
  
  <p>Unlike a <a href="https://docs.flutter.io/flutter/material/MaterialApp-class.html" rel="noreferrer">MaterialApp</a>, CupertinoApp has no property to set the theme.</p>
  
  <p>MaterialApp with theme property:</p>
  
  <pre><code>void main() =&gt; runApp(MyApp());
  
  class MyApp extends StatelessWidget {
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: MyHomePage(title: 'Flutter Demo Home Page'),
      );
    }
  }
  </code></pre>
  
  <p>CupertinoApp without theme property:</p>
  
  <pre><code>void main() =&gt; runApp(MyApp());
  
  class MyApp extends StatelessWidget {
    // This widget is the root of your application.
    @override
    Widget build(BuildContext context) {
      return CupertinoApp(
        title: 'Flutter Demo',
        // theme: ThemeData(
        //   primarySwatch: Colors.blue,
        // ),
        home: MyHomePage(title: 'Flutter Demo Home Page'),
      );
    }
  }
  </code></pre>
  
  <p>It looks like sb. is working on a <a href="https://github.com/flutter/flutter/pull/23759" rel="noreferrer">CupertinoTheme</a> which actually seems to be a Theme for a MaterialApp and not for a CupertinoApp.</p>
  
  <p>What's the recommended way to define themes and change them during runtime in a Cupertino style app (e.g. Dark and Light Theme)?</p>