Show alert dialog on app main screen load automatically in flutter

Question

I want to show alert dialog based on a condition. Not based on user interaction such as button press event.

If a flag is set in app state data alert dialog is shown

Answer 1

You have to wrap the content inside another Widget (preferably Stateless).

Example:

Change From:

  import 'package:flutter/material.dart';

  void main() {
    runApp(new MyApp());
  }

  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
          title: 'Trial',
          home: Scaffold(
              appBar: AppBar(title: Text('List scroll')),
              body: Container(
                child: Text("Hello world"),
              )));
    }
  }

to this:

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

  void main() {
    runApp(new MyApp());
  }

  class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
          title: 'Trial',
          home: Scaffold(
              appBar: AppBar(title: Text('List scroll')), body: new MyHome()));
    }
  }

  class MyHome extends StatelessWidget { // Wrapper Widget
    @override
    Widget build(BuildContext context) {
      Future.delayed(Duration.zero, () => showAlert(context));
      return Container(
        child: Text("Hello world"),
      );
    }

    void showAlert(BuildContext context) {
      showDialog(
          context: context,
          builder: (context) => AlertDialog(
                content: Text("hi"),
              ));
    }
  }

Note: Refer here for wrapping show alert inside Future.delayed(Duration.zero,..)