Flutter is one the most popular User Interaction frameworks and SDKs for developing Android, iOS, web, and desktop apps. It's popular for being an extremely robust tool that offers a wide range of cutting-edge solutions for Mobile Development. In 2021, it was the leader in Cross-Platform Mobile Application Development, even surpassing React Native apps! 

Flutter is a great choice among developers because it provides strong typing and compiles native machine code. That translates to a smooth developer experience and outstanding User Interfaces and graphics. These are only a few reasons big companies like Toyota, BWM, Ubuntu, Tencent, and iRobot have bet on it. Even Microsoft recently contributed greatly to Flutter, giving it foldable support features. So, let's explore why Flutter is so powerful and popular among the community of developers!

What is Flutter?

The Flutter technology is a powerful UI Software Development Kit (SDK) that uses Dart to create beautiful apps with a single codebase. The ultimate UI framework for developing world-class web applications, React.js, inspired Google to develop Flutter in 2017, introducing a new advanced approach to developing mobile applications.

You can think of Flutter's layout as a widget tree that works as the building blocks to create any feature you can imagine for your mobile app. The best part is that its documentation has dozens of pre-built widgets you can use to get started in the blink of an eye.

Fun fact: Flutter is British slang for gambling! "Have a flutter" often works as a synonym for having a bet, normally in horse racing. However, that can't be any further from reality in Software Development. If you've chosen Flutter for cross-platform solutions, you can be 100% sure you've made an excellent choice. If you want to build a mobile app for Android and iOS, the decision is a no-brainer. There are over 700,000 Flutter apps in the Play Store for a reason!

What is a Widget in Flutter?

Widgets are the true essence of any Flutter application. Everything is a widget in Flutter. These highly composable and customizable objects represent all the UI elements of your application. We mentioned that Flutter's layout is a widget tree because every app starts with a root widget that defines its UI structure. 

Then, you continue designing the UI nesting of the flutter widgets within the root widget and nesting more widgets within them. This way, like React Native, Flutter follows a declarative approach to creating smooth animations and UIs. Before jumping on the two main types of widgets, take a look at this diagram that illustrates a standard app widget tree.Flutter Stateless Widgets.

In simple terms, a stateless widget is an element that acts without keeping track of any changing values. They don't have any internal state that changes over time and don't depend on users' interactions. That explains why they named them Stateless and described them as immutable.

You may think it's not cool to implement static elements. Yet, there are plenty of applicable cases for stateless widgets. They're perfect for app design elements, like icons, buttons, text, navigation bars, images, menus, cards, alerts, and progress indicators. You can create a stateless widget by extending the StatelessWidget class and overriding the build() method.

What is a Flutter Stateful Widget?

Unlike stateless widgets, stateful widgets are dynamic elements that respond to specific events or users' interactions, changing or updating their internal data. This way, they modify their data and update the User Interface in response to those events and interactions. There are plenty of use cases for stateful widgets. Some include forms, animations, checkboxes, tabs, timers, counters, and game items. You can create a stateful widget by extending the class StatefulWidget as you override the build() method.

How Does Flutter Work?

As mentioned, Flutter uses Dart to bring top-notch cross-platform applications to life. Dart is a strongly typed, general-purpose, easy-to-learn, optimized language. Further, it supports Ahead-Of-Time (AOT), Just-In-Time (JIT) compilation, and database integration, allowing one to compile source code to native code. As a result, Flutter not only offers seamless flexibility to build high-performance, pixel-perfect applications for mobile platforms but also reduces development costs.

Dart is also compatible with popular Integrated Development Environments (IDEs), including Visual Studio Code. That means you can access multiple plugins to improve your developer experience. Another cool thing about Dart is it has a great package manager called Pub. It comes with a ton of reusable libraries optimized for Flutter and Dart. Developers love it because of its simple syntax and ease of use.

This way, it greatly streamlines the management of dependencies. Flutter had its own high-performance 2D rendering engine developed by Google, Skia Graphics, to render the widget tree that defines the UI. Yet, Flutter's new version (3.10) replaced Skia with Impeller, a long-awaited renderer that leverages app performance and modern graphics Application Programming Interfaces (APIs).

How To Get Started With Flutter?

Needless to say, you must have a strong understanding of Dart before downloading the Flutter SDK. Moreover, ensure you have an IDE with strong support for Dart and Flutter plugins. Flutter's official website recommends Xcode if you're on a Mac and Android Studio if you're on Linux or Windows operating systems. Yet, Visual Studio Code is also a wonderful option.

This framework uses Git for updates and upgrades. Thus, you'll have to install Git separately if your IDE doesn't include it out of the box. Then, you can download and install the Flutter SDK following the steps you require for the OS. You can quickly get started by following these simple steps:

1. Open your terminal or command prompt and run Flutter create my_app. Then, you can quickly navigate to your project directory by running cd my_app.

2. Open the main.dart file inside the lib folder. You'll start building your app in that file. You can replace the existing default code with, for instance, the following:

The main() function is the app's entry point. It calls runApp() and passes an instance of CoffeeApp as the root widget of the app. CoffeeApp is a stateless widget that represents the root of our coffee-themed app and returns a MaterialApp widget. MaterialApp is in charge of the app's basic visual appearance and behavior. It takes a title parameter and a home parameter.

The Scaffold widget provides a basic app structure with an app bar and a body. The AppBar widget represents the app bar at the top of the screen and displays a title. The body property of the Scaffold contains the app's main content. It's a Center widget that displays a Text widget with the text "Brewing Happiness, one cup at a time!".

3. The last step is to run the app with flutter run.

A quicker way to get started will let you test your. You can activate the hot reload feature by simply entering the lowercase "r" in the terminal. This way, you'll instantly see the changes in the UI as you edit your piece of code. If you're using Android Studio, you can use the lightning icon on the top bar to activate the hot reload functionality, which is a development feature that allows you to see real-time changes. You can also use DartPad, which has a beautiful UI that allows you to edit and run Flutter code in the browser.

Pros and Cons of the Flutter Framework

Pros of Flutter Development

● Single-Code Base. Flutter is a cross-platform development framework and SDK that uses the same UI and business logic across different platforms. These key features of Flutter allow developers to build top-notch Android, iOS, desktop, and web apps in the same project.
● Fast Development. The large set of ready-made widgets, IDE support, seamless integration with third-party services, and the hot reload feature facilitate rapid development cycles. Plus, it creates an awesome experience for developers since they don't have to make a single widget from scratch.
● Great Performance. This is a critical advantage of Flutter's system. The framework can make direct API calls to the target platform in their native language, giving developers an easy, productive way to build and deploy cross-platform, high-performance Flutter projects for Android and iOS.

Cons of Flutter Development

● Relatively New. Despite its popularity, not many developers know Dart outside of Flutter, forcing developers who started with other techs to learn another language to use Flutter. Additionally, it has a limited number of third-party libraries.
● Nested Widgets. Earlier, we mentioned that apps with Flutter begin with a widget that developers nest with more widgets as they need more functionalities. That can result in a fairly deeply nested widget tree that can be hard to follow.
‍● Larger File Size. The size of Flutter apps tend to be larger, which can be unattractive for users with limited storage space. That's due to the debug build in the Flutter app development. Yet, this size has a minor impact on users in the production phase.

Final Thoughts

Flutter is an open-source framework which offers out-of-the-box tooling, such as material design and pre-built widgets, that greatly accelerate development times and reduce maintenance costs. In this manner, it can help small teams and businesses launch stunning, high-quality apps, or even MVPs, in record completion times. As a Full-Cycle Development Agency, we highly recommend Flutter for cross-platform app development because of its look, feel, and high level of performance for a wide range of devices.