Flutter tip: When you want to make initState or build an async method, think FutureBuilder

As a note to my Future Self, any time you’re working with Flutter and you want to try to make initState or build an async method — or try to use the then method on a Future inside initState or build — what you probably really want is to use a FutureBuilder inside the build method, something like this:

Widget build(BuildContext context) {

  return Scaffold(
    appBar: AppBar(
      title: const Text("Notification Preferences"),
    body: FutureBuilder<Map<String, dynamic>>(
      future: SharedPreferencesHelper.getAllPrefs(),
      builder: (BuildContext context, AsyncSnapshot snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {

This is true with the Flutter shared_preferences library, as well as any other data that may take a long time to retrieve, such as reading from a database or REST data source.

Update: You may also want another Flutter async builder, such as StreamBuilder.