Flutter and Dart Create Dialog Widget

Flutter and Dart provide us a comman tool for developement of the mobile app for Android and IOS platform.  As mobile app developer we often required to implement the Dialog to so quick action, some alert msg and more to the user. In Simple word Dialogs are used to inform users about a task and can contain critical information, require decisions, or involve multiple tasks. So in this post we are going to explore the several type of the Dialoag and its implementation in Flutter. 

Type of Dialog

We have three types of dialog that Flutter and Dart SDK platform provide us.

• Alert Dialog -- To show some content and action input from the end-user
• Simple Dialog -- Its have lots customization option to show the dialog
• About Dialog -- Dialog to show about us with icon and text.

Alert Dialog and its implementation in Flutter and Dart

First of all, we are going to implement the alert dialog. If you are looking to show the dialog then I am sure you have good knowledge about the dart and flutter and you have already a running project, if not then you can refer our earlier post to get started Creating a Cross-platform Mobile App with Flutter and Dart.

Let's create a function and button in main.dart file to show the dialog. Below is a simple function which will show the Alert Dialog and will pop out when the user tab on the action FlatButton.

Future<void> _showDialog() async {
      return showDialog<void>(
        context: context,
        barrierDismissible: false, // user must tap button!
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('Alert Dialog Demo In Flutter'),
            content: SingleChildScrollView(
              child: ListBody(
                children: <Widget>[
                  Text('Alert Dialog!.'),
                  Text('You are Loving Flutter and Dart, is I am Right?'),
                ],
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text('Yes I Am'),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ],
          );
        },
      );
  }

Now, we need to add a button to our home widget view to show the Alert Dialog when user tab on the button.

 RaisedButton(
              color: Colors.blue,
              child: Text("Show Dialog",style: new TextStyle(fontSize: 24,color: Colors.white),),

              onPressed: () {
                _showDialog();
              },
            ),

The full example of the Alert Dialog in Flutter

import 'package:flutter/material.dart';

void main() => 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 Dialog Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title;

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

class _MyHomePageState extends State<MyHomePage> {


  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(

        title: Text(widget.title),
      ),
      body: Center(

        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[

            RaisedButton(
              color: Colors.blue,
              child: Text("Show Dialog",style: new TextStyle(fontSize: 24,color: Colors.white),),

              onPressed: () {
                _showDialog();
              },
            ),
          ],
        ),
      ),

    );
  }



    Future<void> _showDialog() async {
      return showDialog<void>(
        context: context,
        barrierDismissible: false, // user must tap button!
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('Alert Dialog Demo In Flutter'),
            content: SingleChildScrollView(
              child: ListBody(
                children: <Widget>[
                  Text('Alert Dialog!.'),
                  Text('You are Loving Flutter and Dart, is I amRight?'),
                ],
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text('Yes I Am'),
                onPressed: () {
                  Navigator.of(context).pop();
                },
              ),
            ],
          );
        },
      );
  }
}

So, we have created an Alert Dialog which will get dismissed as soon as user tab on the "Yes I am" Flat button.

Alert Dialog with Positive and Negative Button in Flutter

Let's create another Alert Dialog which will show the Negative and Positive button both and once the user will tab the option a specific function can run.

enum Option{
  positive,
  negative
}

.We also need to change our Future _showDailog function as like below. In this dialog, a switch statement is used to decide which option has been pressed.

   Future _showDialog() async {
      switch (await  showDialog<Option>(

        context: context,
        barrierDismissible: false, // user must tap button!
        builder: (BuildContext context) {
          return AlertDialog(
            title: Text('Alert Dialog Demo In Flutter'),
            content: SingleChildScrollView(
              child: ListBody(
                children: <Widget>[
                  Text('Alert Dialog!.'),
                  Text('You are Loving Flutter and Dart, is I amRight?'),
                ],
              ),
            ),
            actions: <Widget>[
              FlatButton(
                child: Text('Yes I Am'),
                onPressed: () {
                  /// perform any action
                  Navigator.of(context).pop(Option.positive);
                },
              ),
              FlatButton(
                child: Text('No'),
                onPressed: () {
                  /// perform any action
                  Navigator.of(context).pop(Option.negative);
                },
              ),
            ],
          );
        },
      )
      )
      {
      case Option.negative:
      // Perform Any action
      print("${Option.negative}");
      break;
      case Option.positive:
      // Perform Any action
      print("${Option.positive}");
      break;
      }
  }

Alert Dialog with Postive and Negative Button

Simple Dialog

Simple Dialog provides the functionality to choose the option from several available options. For example, you have just asked a question to the user 'Which is your Favorite" OS' and provide the list of the OS to choose.

First of all, create our choice for the user using the enum.

enum OS{
  Android,
  Windows,
  IOS,
  None
}

Let's create our Simple Dialog as given below.

Future<void> _simpleDialog() async {
    switch (await showDialog<OS>(
        context: context,
        builder: (BuildContext context) {
          return SimpleDialog(
            title: const Text('Which is your Favourite OS?'),
            children: <Widget>[

              SimpleDialogOption(
                onPressed: () { Navigator.pop(context, OS.Android); },
                child: const Text('Android'),
              ),
              SimpleDialogOption(
                onPressed: () { Navigator.pop(context, OS.IOS); },
                child: const Text('IOS'),
              ),
              SimpleDialogOption(
                onPressed: () { Navigator.pop(context, OS.Windows); },
                child: const Text('Windows'),
              ),
              SimpleDialogOption(
                onPressed: () { Navigator.pop(context, OS.None); },
                child: const Text('None of the Above'),
              ),

            ],

          );
        }
      )
    )
    {
      case OS.Android:
        print("I am Fan of the Android");
        break;
      case OS.Windows:
       print("I am Windows Lover");
        break;
      case OS.IOS:
        print("I Like IOS.}");
        break;
      case OS.None:
        print("None of the above.");
        break;
    }
  }

Now, call this _simpleDailog function from anywhere to show the dialog.

Simple Dialog in Flutter

About Dialog in Flutter

About Dialog are used to show the details of the application and used software and platform to develop the application. Its include the name, icon, etc and one view license button. So let's create a function to show the about dialog in Flutter.

Future<void> _showAboutDialog() async{
    showAboutDialog(
      context:  context,
      applicationName: "Dialog Demo",
      applicationVersion: "1.2.1",
      applicationIcon: new Icon(Icons.android,color: Colors.green,),
      applicationLegalese: "www.nplix.com",
      children: <Widget>  [
        Text("Welcome to NPLIX.com"),
    ],
    );
}

About Dialog

When you tap on the View Licenses it will open the license details in new screen like given below.

Wrapping Up

So in this post, we have created three types of dialog in flutter Alert Dialog, Simple Dialog and About us Dialog. If have any query on this please ask in the comment section. You can further learn more about these on the Flutter page.