// Check out the source page for step-by-step walkthrough.

​

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    return MaterialApp(

        home: Scaffold(

           appBar: AppBar(

            title: Text('Call a Function Everytime When App Starts')), 

            body: Center(

            child: Alert()

           )

          )

        );

  }

}

class Alert extends StatefulWidget {

  AlertState createState() => AlertState();

}

class AlertState extends State {

  @override

  void initState() {

    showAlert(context);

    super.initState();

  }

  Future showAlert(BuildContext context) async {

    await Future.delayed(Duration(seconds: 6));

    showDialog(

    context: context,

    builder: (BuildContext context) {

      return AlertDialog(

        title: new Text('Welcome To Our App :) .'),

        actions: <Widget>[

          FlatButton(

            child: new Text("OK"),

            onPressed: () {

              Navigator.of(context).pop();

            },

          ),

        ],

      );

     },

    );

  }

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      body: Center(

        child: Text('Call A Function Automatically When App Starts Everytime',

        style: TextStyle(fontSize: 22,), textAlign: TextAlign.center,)

      ),

    );

  }

}

​