How to Design Responsive Apps Using Flutter Adaptive Scaffold Package

Hello, fellow developers!

As we know, Flutter has emerged as a popular choice for building beautiful and highly functional cross-platform apps. You can cater to Android, iOS, and web users with a single codebase. As the user base and the range of devices continue to diversify, adapting to different screen sizes and operating systems is increasingly crucial.

Close your eyes and imagine a scaffold - a temporary structure used to support work crews and materials to facilitate the construction of buildings. This image is pretty close to what a Scaffold is in Flutter. It's a class that implements the basic material design visual layout structure.

What is a Flutter Scaffold?

The Scaffold is a class in Flutter that implements the basic material design visual layout structure. It's like a blank canvas developers use to construct their mobile applications. It provides several slots for different parts of an application, such as the AppBar (a horizontal bar at the top), Drawer (a side menu typically hidden off-screen), BottomNavigationBar , **SnackBar** (used to display notifications), and many more. Let's consider Scaffold as the primary set of operations we can use to structure the layout of our screens.

But more than a simple Flutter Scaffold might be required when developing applications for multiple screen sizes and orientations. That's why the Flutter adaptive scaffold is a potent tool designed to create adaptive layouts that adjust to different mobile device screen widths.

Basics of Flutter Adaptive Scaffold

What makes Flutter adaptive scaffold unique? Unlike the traditional Flutter Scaffold, the Flutter adaptive scaffold helps you structure your app to automatically adjust its layout based on the screen size or the device screen it's running on.

Remember, each mobile or tablet device has a primary screen of specific dimensions. The adaptive scaffold class in Flutter helps your app to respond to this primary screen size, ensuring your app looks as intended on all device screens. This is particularly important as Flutter allows you to develop desktop apps, further diversifying your user's devices.

Flutter adaptive scaffold intelligently understands the available screen size; whether your application runs on a mobile device in portrait mode, landscape mode, or even on a desktop, it adapts accordingly.

Let's create a basic example. First, start your new Flutter project by using the following command in your terminal:

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1flutter create adaptive_app

Open the main dart file, and delete the predefined code. Replace it with the code below to form a simple app:

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1void main() {
2  runApp(const MyApp());
3}
4
5class MyApp extends StatelessWidget {
6  const MyApp({Key? key}) : super(key: key);
7
8  @override
9  Widget build(BuildContext context) {
10    return const MaterialApp(
11      home: Scaffold(
12        appBar: AppBar(
13          title: Text('Flutter Adaptive Scaffold Tutorial'),
14        ),
15      ),
16    );
17  }
18}

Adaptive Layouts in Flutter

In Flutter, adaptive layouts are the base of any responsive design. They are like a switch that adjusts the layout depending on the screen's width or orientation. The Flutter team has introduced the LayoutBuilder class to create adaptive layouts. This class provides Builder, which offers the current BuildContext context and BoxConstraints, allowing you to determine the current screen width or size.

Let's look at an example where we would like to display a list that could be either horizontal or vertical based on the screen width. Flutter allows you to handle this with a LayoutBuilder like so:

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1LayoutBuilder(
2  builder: (BuildContext context, BoxConstraints constraints) {
3    if (constraints.maxWidth > 600) {
4      return GridView.count(
5        crossAxisCount: 2,
6        children: _getListItems(),
7      );
8    } else {
9      return ListView(
10        children: _getListItems(),
11      );
12    }
13  },
14)

In this code snippet, we check the screen width in the builder function. If it's more than 600 pixels, a GridView is returned. Otherwise, a ListView is returned.

Flutter Adaptive Navigation Scaffold

The Flutter Adaptive Navigation Scaffold is a package made by the Flutter team, designed to simplify the creation and usage of NavigationRail, BottomNavigationBar, and Drawer. These widgets act as the navigation bar and are automatically adapted according to the screen width.

To add this package, insert this line into your pubspec.yaml file:

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1dependencies:
2  adaptive_navigation: ^0.0.4

Then, run flutter deps get in your console to fetch the package.

Time to modify the Scaffold to utilize the AdaptiveNavigationScaffold. In the dart file, replace your scaffold with the following code:

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1return AdaptiveNavigationScaffold(
2  selectedIndex: _selectedIndex,
3  destinations: const [
4    AdaptiveScaffoldDestination(title: 'Home', icon: Icons.home),
5    AdaptiveScaffoldDestination(title: 'Settings', icon: Icons.settings),
6  ],
7  body: _getScreen(),
8);

The AdaptiveNavigationScaffold automatically selects the correct widget (Drawer, BottomNavigationBar, or NavigationRail) based on the screen width.

Getting Started with Flutter_adaptive_scaffold Package

Now that we have a basic understanding of the adaptive layouts and Flutter Adaptive Navigation Scaffold let's dive into the functionalities provided by the Flutter Adaptive Scaffold package.

To utilize the Flutter Adaptive Scaffold package in your Flutter apps, add it as a dependency in your pubspec.yaml:

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1dependencies:
2  flutter:
3    sdk: flutter
4  flutter_adaptive_scaffold: ^version

Once added, run the following command to fetch the package:

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1flutter packages get

You are now ready to import and use the Flutter adaptive scaffold.

In your current dart file, import the flutter_adaptive_scaffold:

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1import 'package:flutter_adaptive_scaffold/flutter_adaptive_scaffold.dart';

The AdaptiveScaffold widget allows us to create a Scaffold whose layout automatically adapts across different screen widths. It adds a nice layer of abstraction, providing a body, title, actions, drawer, floatingActionButton and bottomNavigationBar that can be customized based on usage.

Using const Icon in Flutter Adaptive Scaffold

Now that the basic setup is complete let's talk about icons. Icons are crucial in any app, guiding users and enriching the app experience. In Flutter, the const icon is a graphical representation that takes input of type IconData. Icons are identified by their name, as listed here.

Let's see how to integrate the const Icon into our scaffold.

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1AdaptiveScaffold(
2  title: const Text('Adaptive Scaffold'),
3  actions: [
4    Padding(
5      padding: const EdgeInsets.symmetric(horizontal: 16.0),
6      child: const Icon(Icons.add),
7    ),
8  ],
9  destinations: const [
10    AdaptiveScaffoldDestination(title: 'Item 1', icon: Icons.add),
11    AdaptiveScaffoldDestination(title: 'Item 2', icon: Icons.straighten),
12  ],
13  body: ...,
14)

In the code above, AdaptiveScaffoldDestination items are used in the navigation bar and each item accepts a title and an icon. const Icon(Icons.add) represents an icon in the app bar and serves as an action item.

Each icon added through const Icon in Flutter adaptive scaffold enhances the user experience by providing an intuitive user interface.

Final String & BuildContext Context in Flutter_adaptive_Scaffold

Let's discuss the roles of the final string and BuildContext context in our Flutter adaptive scaffold.

A final string variable is a constant whose value is assigned during its declaration and can't be change afterwards. It plays a vital role in storing constant values like the title of a screen, user inputs and identifiers. For instance:

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1final String title = 'Flutter Adaptive';

On the other hand, BuildContext context works like a handle to the widget's location in the widget tree. This context is used for looking up InheritedWidgets. Let's see how we can access the BuildContext context:

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1class MyApp extends StatelessWidget {
2  const MyApp({Key? key}) : super(key: key);
3
4  @override
5  Widget build(BuildContext context) {
6    return const MaterialApp(
7      home: Scaffold(
8        appBar: AppBar(
9          title: Text('Flutter Adaptive'),
10        ),
11      ),
12    );
13  }
14}

Here, BuildContext context is used as a parameter for the build method of MyApp.

The final string and BuildContext context impact your adaptive design's overall structure and functionality.

Building a Sample Adaptive App

With all the basics covered, it's finally time to leverage the Flutter adaptive scaffold and create an adaptive app. Let's work on a simple example.

Create a new folder in the lib directory named screens. Create two new Dart files inside this folder, home_screen.dart, and settings_screen.dart.

Create a Stateless widget in each file that returns a simple Center widget. For instance, in the home_screen.dart file:

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1class HomeScreen extends StatelessWidget {
2  const HomeScreen({Key? key}) : super(key: key);
3
4  @override
5  Widget build(BuildContext context) {
6    return const Center(
7      child: Text(
8        'Home Screen',
9        style: TextStyle(fontSize: 24),
10      ),
11    );
12  }
13}

Now, in your main.dart, replace _getScreen method with the following:

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1Widget _getScreen(BuildContext context, int index) {
2  switch (index) {
3    case 0:
4      return const HomeScreen();
5    case 1:
6      return const SettingsScreen();
7    default:
8      return const Text('Something went wrong');
9  }
10}

Then, replace _AdaptiveNavigationScaffoldState with:

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1class _AdaptiveNavigationScaffoldState extends State<AdaptiveNavigationScaffold> {
2  int _selectedIndex = 0;
3
4  @override
5  Widget build(BuildContext context) {
6    return AdaptiveNavigationScaffold(
7      selectedIndex: _selectedIndex,
8      destinations: const [
9        AdaptiveScaffoldDestination(title: 'Home', icon: Icons.home),
10        AdaptiveScaffoldDestination(title: 'Settings', icon: Icons.settings),
11      ],
12      body: _getScreen(context, _selectedIndex),
13      onDestinationSelected: (int index) {
14        setState(() {
15          _selectedIndex = index;
16        });
17      },
18    );
19  }
20}

With this setup, when you click 'Home' or 'Settings' from the navigation menu, it routes to the respective screen.

Testing and Debugging in Flutter Adaptive Scaffold

Great job on building the app! However, our work still needs to be completed. Testing is a crucial part of the development process in the Flutter adaptive scaffold.

Flutter provides a "hot reload" feature that aids in testing functionality in real-time on multiple devices simultaneously. Check your adaptive app on different platforms like iOS and Android and inspect its behavior on other devices with varying screen sizes.

For debugging, Dart DevTools come to the rescue. Dart Devtools is a suite of debugging and performance tools. This feature makes it easy to identify visual issues, especially when your adaptive layout behaves unexpectedly on specific screen sizes.

Make sure your adaptive scaffold is functional and responsive across different devices, and make the necessary changes.

Conclusion

There you have it - a comprehensive guide on building an adaptive app using the Flutter adaptive scaffold. Flutter provides the power to build beautiful, highly customized apps that seamlessly adjust to multiple devices' screen sizes without much hassle.

Adaptive app design is more than just a trend; it’s necessary as the number of platforms and devices grows. Harnessing the power of Flutter's adaptive scaffold and its accompanying functionalities, you can offer a robust, responsive, and user-friendly app, no matter the platform or device it’s used on.

Equipped with this knowledge, it's your turn to unleash the power of adaptive design and create splendid app experiences that your users will love!

Key Takeaways

• Flutter adaptive scaffold optimizes your app layout across different screen sizes and orientations.
• Final string and BuildContext context can significantly impact your adaptive design's overall structure and functionality.
• The Flutter adaptive scaffold uses const icons for an intuitive user interface.
• Ensure proper testing across different devices to verify your app's adaptability.

Embrace the world of adaptability and bring unique experiences to users around the globe with the Flutter adaptive scaffold!

References

• Official Flutter Documentation
• Flutter adaptive scaffold package