Basic knowledge, core concepts and some practical development skills of Flutter

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Preface

In recent years, I have been engaged in flutter-related work, and I have always wanted to write a complete project structure from zero to one. Since I have never had time, now that I think about it, I might as well start slowly first.
The introduction of this article serves as the starting point of this series of articles. I hope you will like it.

A Deep Dive into Flutter App Development

Flutter is an open source cross-platform mobile application development framework developed and maintained by Google. It allows developers to use a single code base to build high-performance, beautiful and fast mobile applications that can run on multiple platforms including iOS, Android, web and desktop. This article will delve into the basics, core concepts, and some practical development techniques of Flutter application development.

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1. What is Flutter?

Flutter is a UI framework using the Dart programming language. What is unique about it is that it uses a component model called "widget" to build user interfaces. Flutter’s Widgets are immutable, meaning that once they are created, they do not change. This immutability helps build predictable, maintainable, and performant applications.

Dart programming language

Before we dive into Flutter, let’s first understand the Dart programming language. Dart is a modern programming language developed by Google and used for writing Flutter applications. Dart has the following characteristics:

• High performance: Dart is designed to be a fast-execution language, which makes Flutter applications perform well in terms of performance.
• Static type checking: Dart supports static type checking, which helps catch errors during development and improve code quality.
• Asynchronous programming: Dart has built-in support for asynchronous programming, making it easier to handle asynchronous tasks.
• Automatic garbage collection: Dart has a garbage collection mechanism that eliminates the need for developers to manually manage memory.

Widget component model

In Flutter, everything is a Widget. Widgets are the building blocks of an application. They can be basic UI elements (such as text, buttons, images) or complex layouts (such as lists, grids, pages). Widgets can contain other widgets, forming a widget tree.

Widgets in Flutter are divided into two categories:

• StatelessWidget: These are immutable Widgets that never change once created. They are typically used to display static content such as text or images.
• StatefulWidget: These are stateful Widgets, which can change state during their life cycle. They are typically used to handle user interaction and dynamic data.

The widget tree is the visual representation of a Flutter application, and Flutter builds the user interface based on the widget tree. Here is a simple example that demonstrates how to create a Flutter Widget containing text:

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('My Flutter App'),
        ),
        body: Center(
          child: Text('Hello, Flutter!'),
        ),
      ),
    );
  }
}

In this example, MyAppis a StatelessWidget, which returns a ScaffoldWidget containing a title and text, with the text being Textthe Widget.

2. The core concepts of Flutter

To understand Flutter in depth, let us look at some core concepts that play a key role in app development.

MaterialApp and Scaffold

In Flutter, MaterialAppand Scaffoldare common top-level widgets. MaterialAppDefines the basic features of the application, such as themes, navigation, and route management. ScaffoldIt defines the basic layout structure of the application, including the application bar, drawer, bottom navigation bar, etc.

Widget life cycle

Each Widget has its own life cycle. For example, StatefulWidgetwith the following lifecycle methods:

• createState: Create a state object associated with this Widget.
• build: Build the UI representation of the Widget.
• initState: Called when a state object is inserted into the tree, usually used for one-time initialization.
• didUpdateWidget: Called when the Widget configuration changes.
• dispose: Called when a state object is removed from the tree, usually used for resource cleanup.

Understanding these lifecycle methods helps you correctly handle changes in state and data in your application.

layout and arrangement

Flutter provides multiple ways to layout and arrange widgets. One is to use Rowwidgets Columnto create horizontal and vertical layouts. Another is to use Containerwidgets Stackto create custom layouts. For example, Containerit can be used to create a rectangular container with margins, padding, and background color, and Stackit can be used to stack multiple Widgets.

Row(
  children: <Widget>[
    Icon(Icons.star),
    Icon(Icons.star),
    Icon(Icons.star),
  ],
)

Status management

In most applications, there is a need to manage and share data and handle user interaction. Flutter provides a variety of ways to manage state, including:

• setState: Used to StatefulWidgetupdate status in and trigger a rebuild.
• Provider: Used to share data and manage global status.
• Bloc: Used to implement business logic and state management.
• GetX: Used to simplify state management and dependency injection.

Choosing the appropriate state management method depends on the size and needs of your application.

3. Practical development skills

In addition to understanding the core concepts of Flutter, here are some practical development tips that can help you build Flutter applications more efficiently:

Use Hot Reload

Flutter's hot reload feature makes the development process faster and smoother. It allows you to instantly see the effects of UI and code changes without restarting the application. Just click the hot reload button in the IDE or run flutter hot reloada command.

Adapt to different screen sizes

Flutter provides a wealth of screen adaptation tools and widgets to ensure that your application runs well on devices of different sizes and resolutions. Use MediaQueryto obtain device information, Expandedand use Flexiblewidgets such as and to create adaptive layouts.

Using Flutter plug-in

The Flutter community provides a large number of plugins that can add various features to your application, such as geolocation, camera, storage and network requests. pub.devFlutter’s official plug-ins and third-party plug-ins can be found on .

Learn Flutter DevTools

Flutter DevTools is a set of tools for analyzing, debugging, and optimizing Flutter applications. It includes Flutter Inspector, Timeline, Memory, Network and other useful tools. Learning to use these tools can help you better understand and optimize your application performance.

Follow Flutter best practices

The Flutter community provides a set of best practices and design guidelines that can help you write high-quality, easy-to-maintain code. These guidelines include how to organize your project structure, naming conventions, coding style, and testing.

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Summarize

Flutter is a powerful mobile application development framework that combines the modern programming language Dart with the flexible Widget component model. With a deep understanding of Flutter's core concepts and practical development techniques, you can build high-performance, beautiful, and cross-platform mobile applications. Whether you are a beginner or an experienced developer, you can create amazing apps by learning and mastering Flutter.

In this article, we explore the basics, core concepts, and some practical development techniques of Flutter. If you want to learn Flutter in depth, it is recommended to consult Flutter official documentation and tutorials, and participate in discussions and activities in the Flutter community. I wish you success in your Flutter app development journey!