The basics of Flutter

Discover the basics to understand how Flutter. Learn key concepts, the programming language, how to create user interfaces and much more.

To master the powerful Flutter tool, it's essential to understand its fundamentals. In this article, we'll take you through the basics of how Flutter works. We'll explore the key principles behind this revolutionary technology for cross-platform application development. Whether you're a seasoned developer or a novice in the field, this reading will give you a better understanding of Flutter and its essential functionalities. Get ready to dive into the world of Flutter and discover new perspectives on application development.

What is Flutter?

Definition

Flutter is an open-source framework developed and maintained by Google. It enables create mobile applications for iOS, Android and other platforms from a single source code. With Flutter, developers can build attractive, responsive user interfaces, smooth animations, and easily manage the state of their application.

History

Flutter was first announced by Google in 2015 and entered alpha release in 2017. Since then, it has seen rapid adoption in the developer community thanks to its high performance and productivity. Flutter has been used to create many popular applications, such as Google AdsAlibaba, Hamilton, and many others.

Objectives

Flutter's main objectives are to simplify the development of cross-platform applications, improve application performance and responsiveness, and provide a single point of contact for all users. user experience quality. Flutter also aims to enable developers to easily customize the appearance and behavior of their applications, while offering great flexibility in managing application state.

Flutter's key concepts

Widgets

Widgets are the basic elements of Flutter and represent everything visible in an application's user interface. Every element, from a simple button to the application's main screen, is a widget. Widgets can be combined and prioritized to form complex user interfaces.

The "everything is a widget" concept

Flutter's fundamental philosophy is that "everything is a widget". This means that every element of the user interface is represented by a widget, including more complex elements such as fonts, styles, layouts and user interactions. This approach simplifies the construction and customization of user interfaces.

The rendering engine

Flutter uses its own rendering engine to display user interfaces smoothly and responsively. Flutter's rendering engine, called Skia, is optimized to deliver high performance and smooth animations. It also provides precise control over the graphics and rendering of user interface elements.

The responsiveness framework

Flutter's reactivity framework manages UI updates in response to application state changes. When a state changes, Flutter updates the relevant widgets efficiently, minimizing unnecessary recalculations. This ensures high performance even for complex user interfaces.

Flutter's programming language

Dart

Flutter uses Dart as its main programming language. Dart is a modern, high-performance language developed by Google, designed specifically for the mobile application development and web applications. Dart offers clear, concise syntax, fast compilation and support for advanced features such as static typing and asynchronous futures.

Dart features

Dart offers a number of features that make it ideally suited to the development of Flutter applications. These include object-oriented syntax, the ability to define classes and interfaces, asynchronous state management thanks to futures and Streams, the ability to create anonymous (lambda) functions and closures, and support for multiple inheritance thanks to mixins.

Comparison with other languages

Compared to other languages commonly used for the mobile developmentDart offers a number of advantages over other programming languages such as Java, Kotlin and Objective-C/Swift. In addition to its high performance, Dart offers increased productivity thanks to its fast compilation and optional dynamic typing. What's more, Dart's clear, concise syntax makes code easier to read and understand, reducing the risk of errors and speeding up development.

Application development with Flutter

Installing Flutter

To start developing applications with Flutter, you first need to install the Flutter SDK (Software Development Kit). The Flutter SDK is available free of charge and can be downloaded from the official Flutter website. Once the SDK has been installed, it is necessary to configure the development environment.

Configuring the development environment

Flutter is compatible with various IDE (Integrated Development Environment), such as Android StudioIntelliJ IDEA and Visual Studio Code. It is recommended to use an IDE adapted to Flutter, as it facilitates development and offers advanced features such as code completion, debugging and dependency management.

Once you've installed an IDE with the Flutter plug-in, you'll need to configure the path to the Flutter SDK and development tools. This step enables the IDE to recognize Flutter and provide Flutter-specific functionality.

Creating a Flutter project

Once the development environment has been set up, it is possible to create a Flutter project. This can be done from the IDE using a basic project template provided by Flutter, or by using the Flutter command line. When a Flutter project is created, a set of files and directories is generated, providing a basic structure for application development.

Flutter project structure

The structure of a Flutter project is based on the MVC (Model-View-Controller) design model. The application's source code is located in the project's "lib" directory. This directory contains the application's Dart source files, including model, view and controller files. It may also contain other directories to organize the code logically.

Navigation between screens

Navigation between screens is an important part of Flutter application development. Flutter offers several solutions for managing navigation, such as the built-in "Navigator", which lets you push and popper screens onto a navigation "stack". There are also third-party libraries, such as "flutter_bloc" and "GetX", which facilitate navigation management and communication between screens.

Creating user interfaces with Flutter

Basic widgets

Flutter offers a wide range of ready-to-use widgets for creating attractive, functional user interfaces. Basic widgets include buttons, dialogs, images, text fields, lists and much more. These widgets can be customized and arranged to create user interfaces tailored to the needs of the application.

Creating layouts

Flutter offers several widgets for creating and organizing layouts. These include "Container", which lets you define the size, margin and color of an element, "Row" and "Column", which let you create linear layouts, and "Stack", which lets you superimpose elements one on top of the other. These widgets can be combined and hierarchized to create complex user interfaces.

User interaction management

Flutter offers a number of features for managing user interaction, such as gesture detection and interaction animations. With Flutter, it's possible to detect gestures such as taps, swipes and swipes, and trigger corresponding actions. Fluid animations can also be created to make user interactions more visually pleasing.

Themes and styles

Flutter offers a system of themes and styles that allow you to customize the application's appearance in a consistent way. Themes define the colors, fonts and other elements of the user interface, while widget-specific styles allow you to customize their individual appearance. This creates a consistent, professional user experience across the entire application.

State management in Flutter

The concept of state

State management is important in any application, and Flutter offers several approaches to managing state effectively. State represents data that can change during application execution, such as the text in an input field or the status of a button. Flutter offers solutions for managing local and global state in a clear and organized way.

Local government management

To manage local state, Flutter offers various widgets such as "StatefulWidget" and "Provider". These widgets can be used to define local states that can be modified during application execution. When a local state changes, Flutter automatically updates the widgets concerned to reflect the new data.

Global condition management

Global status management is generally performed using third-party libraries such as "Provider", "Redux" or "Riverpod". These libraries enable status to be shared between different widgets, providing centralized management of global status. This facilitates communication between widgets and ensures that state changes are taken into account throughout the application.

The different approaches

There are several approaches to managing state in Flutter, each with its own advantages and limitations. Some developers prefer to use simple solutions such as "setState" to manage local state, while others prefer to use more powerful third-party libraries to manage global state. The choice of approach depends on the specific needs of the application and the developer's preferences.

Animations in Flutter

Basic animations

Animations are essential to make an application more attractive and interactive. Flutter offers native support for basic animations such as transition animations, keyframe animations, rotation animations, scaling animations and many more. These animations can be implemented using various widgets and methods provided by Flutter.

Complex animations

In addition to basic animations, Flutter also offers advanced features for creating complex animations. These include custom animation, which lets you create customized animations using custom interpolation curves, compound animation, which lets you combine several animations to achieve more complex effects, and physical animation, which simulates physical movements such as gravity and friction.

Managing transitions

Flutter also offers tools for managing transitions between different pages or screens within an application. For example, it is possible to animate the transition between two screens using effects such as crossfading, expansion or rotation. These transitions make for a smoother, more pleasant user experience.

Integration of external services and APIs

Access to external resources

In application development, it is often necessary to access external resources such as databases, local files, sensors or online services. Flutter offers native support for accessing these resources through specific libraries. For example, it is possible to access local files using "path_provider", or to consume APIs using "http".

Communication with APIs

Flutter facilitates API communication by offering native support for common communication protocols such as HTTP and WebSocket. Third-party libraries such as "dio" further simplify API communication by providing advanced features such as interceptor management, caching and error handling.

Common integration libraries

To facilitate integration with popular third-party services, Flutter offers a rich ecosystem of integration libraries. For example, there are libraries for integrating authentication services such as Firebase Auth, geolocation services such as Geolocator, or analytics services such as Firebase Analytics. These libraries save development time by offering well-tested, pre-built functionality.

Deploying Flutter applications

The different deployment platforms

Flutter enables applications to be deployed on different platforms, including iOS, Android, the web, and even embedded systems such as Linux and macOS. For each platform, Flutter offers a specific set of tools and features to ensure an optimal user experience. It is also possible to customize the look and feel of the application for each platform.

Generating executable files

Flutter generates executable files for each target platform. For example, for iOS, Flutter generates an IPA file that can be distributed via the App Store, while for Android, Flutter generates an APK file that can be distributed via the Google Play Store. For web deployment, Flutter generates a set of HTML, CSS and JavaScript which can be hosted on a web server.

Testing and validation

Before deploying an application, it is important to test and validate it to guarantee its quality and smooth operation. Flutter offers a set of tools to facilitate unit and integration testing, as well as tools for application validation, such as the "flutter doctor", which checks dependencies and configuration requirements. These tools help identify and resolve potential problems before deployment.

Application stores

To distribute a Flutter application, it is often necessary to publish it on official application stores such as the Apple App Store and Google Play Store. Flutter offers native support for these stores, making it easy to submit and publish the application. Once published, the application is visible and accessible to users, who can download and install it on their devices.

Good development practices with Flutter

Recommended software architecture

Flutter does not dictate a specific architecture, but there are recommended architectures for developing Flutter applications in a structured and maintainable way. Commonly used architectures include the "BLoC" (Business Logic Component) architecture, where business logic is separated from user interface logic. Other architectures, such as "MVVM" (Model-View-Model) or "Clean Architecture", can also be used, depending on the specific needs of the application.

Code organization

Code organization is important for the readability and maintainability of a project. Flutter recommends organizing code using a logical project structure, such as separating source files according to their role (models, views, controllers), or using specific directories for features or application modules. The use of best practices such as breaking down code into reusable widgets and clear code documentation also contribute to better code organization.

Unit and integration testing

Testing is essential to guarantee the quality and stability of a Flutter application. Flutter offers native support for unit and integration tests, making it easy to write and run automated tests. Unit tests verify the correct operation of individual application components, while integration tests test the behavior of the application as a whole. Writing regular tests and executing automated tests contribute to the reliability of the application and the reduction of bugs.

Performance management

Performance management is important to ensure a smooth and responsive user experience. Flutter offers several features to optimize application performance, such as "ahead-of-time" compilation to reduce application launch time, widget and resource caching, and efficient state management. Good development practices, such as the avoidance of costly operations, the use of memory management, and the optimization of animations, also contribute to improving application performance.

In conclusion, Flutter is a powerful and versatile framework for cross-platform application development. Thanks to its key concepts such as widgets, the Dart language, state management, animations and integration of external services, Flutter offers a fluid and productive development experience. Using recommended best development practices, developers can create high-performance, attractive applications for a wide range of platforms.