A Complete Guide to Flutter Architecture

• Mobile
• November 8, 2024

by Parth Pandya

Flutter is one of the most used frameworks to develop apps for multiple platforms. This popularity is attributed to many pros; however, the well-developed architecture is one of the significant factors, setting Flutter apart from the rest. This blog will help you delve deeper into the Flutter architecture patterns to understand how they promote efficient application development.

It depends on a variety of facets; however, the well-developed architecture of a framework promotes high-performance app development, and that’s where Flutter architecture comes into play. Fostering modularity and reusability, the architecture of Flutter enables developers to build apps that perform seamlessly across platforms.

From consistent UI/UX to enhanced customizability, faster development, enriched performance, and reduced maintenance requirements, the Flutter architecture eases app development, ensuring maximized performance and outcomes.

This blog assesses the intricacies of Flutter’s architecture, separated into three primary layers: the framework, the Engine, and the Embedder. It’ll help you understand how each layer operates, allowing you to know the architecture better and make informed decisions in tech selection.

Flutter Architecture Overview

Designed in a layered and extensible system, Flutter architecture tends to exist as a suite of independent libraries, each depending on the underlying layer. There are mainly three layers that form the Flutter architecture, including Framework, Engine, and Embedder. No layer is privileged by access to the layers below. Besides, each part of the framework level is designed in a way that is optional and replaceable.

Flutter Framework

Written in Dart programming language, Flutter tends to be a modern and reactive framework. Developers interact with Flutter via the Flutter framework, which contains a complete set of platforms and fundamental libraries composed of a suite of layers. These layers collectively handle various tasks such as user interactions, animations, and rendering, ensuring smooth performance and platform integration.

• The fundamental classes and building block services like Painting, Animation, and Gestures provide commonly used abstractions on the underlying foundation. 
• The rendering layer offers an abstraction aimed at dealing with the layout. It helps you build the tree of renderable objects. With the tree, updating the layout automatically to reflect changes, you can manipulate these objects dynamically. 
• The widgets layer tends to be a composition abstraction. Every render object in the rendering layer comes with a corresponding class in the widgets layer. Additionally, the widgets layer enables you to define classes’ combinations that you can reuse. At this layer, the reactive programming model is introduced. 
• The Material and Cupertino libraries provide an extensive set of controls that make use of the widget layer’s composition primitives to implement iOS or Material design language.

Flutter Engine

The engine, primarily written in C++, forms the core of the framework and provides the key components needed to run Flutter apps. It rasterizes composite scenes whenever a new scene needs to be painted.

The engine offers a low-level implementation of Flutter’s core API, including graphics (using Impeller in progress for iOS and Skia on other platforms), text layout, accessibility support, plugin architecture, file and network I/O, and a Dart runtime with a compile toolchain.

Embedder

A platform-specific embedder provides an entry point that coordinates with the underlying operating system to access services such as rendering surfaces, input handling, and managing the message event loop. 

The embedder is written in the platform’s appropriate language—C++ and Java/Kotlin for Android, Objective-C or Objective-C++ for iOS and macOS, and C++ for Linux and Windows. Using the embedder, developers can integrate Flutter code into an existing app as a module or use it to build the entire app’s UI.

Anatomy of An Application

Look at the diagram below that gives an overview of the pieces that build a Flutter application. It showcases where the Flutter Engine exists in this stack, highlights API boundaries, and pinpoints the components where the separate pieces reside. The diagram below also clarifies some terminologies commonly used to demonstrate the pieces of a Flutter application.

The documentation defined in the official Flutter documentation is as follows:

Dart App

• Tends to compose widgets into tailored UI.
• Implements business logic.
• Owned and managed by an app developer.

Framework

• Provides high-end APIs, such as widgets, hit testing, text input, gesture detection, and accessibility, to build high-performance apps.
• Constructs the widget tree and translates it into a render tree for the engine to composite into a scene.

Engine

• Rasterizes composited scenes into pixels.
• Offers low-level implementation of the core APIs of Flutter (such as text layout, graphics, and Dart runtime).
• Integrates with a specific platform, making use of the Engine’s Embedder API.
• Tends to expose its functionality to the framework employing the dart:ui API.

Embedder

• Coordinates with the underlying operating system intending to access services such as rendering surfaces, input, and accessibility.
• Manages the event loop to handle input events and rendering updates.
• Exposes platform-specific APIs to integrate Flutter with the operating system and provide services like rendering and input handling.

Runner

• Tends to compose the pieces that are exposed by the platform-specific API of the Embedder into an app package capable of running on the target platform. 
• Part of the application template is created by Flutter Create and owned by the app developer.

Flutter Architecture Best Practices

The Flutter architecture assists you in developing robust mobile apps; however, employing best practices is essential to optimize the benefits. Mentioned below are the best practices for Flutter architecture:

Single Responsibility Principle

Make sure that each widget or class has a single purpose and responsibility so that you can maintain and update code with ease, circumventing potential bugs. 

Dependency Injection

By mitigating the coupling between classes, the dependency injection eases it to test and manage code. It enables you to replace dependencies with no major change to the entire code. 

BLoC (Business Logic Component) Pattern

Employing BLoC tends to separate your UI from your business logic and makes it easy to test and maintain the code. What’s more, it allows you to reuse your business logic across various screens and widgets. 

Code Optimization

Although Flutter is designed to develop high-performance apps, you need to optimize your code for better performance. The performance optimization involves minimizing widget rebuilds, making use of “const” wherever possible, and lessening unnecessary animations and effects.

Use of Stateful Widgets

Stateful widgets tend to be way more complex than stateless widgets, hence opt for using them only when necessary. Consider making use of stateless widgets when you’re able to manage your widget’s state using a simple approach. 

Material Design Guidelines

Flutter involves a library of Material Design widgets, allowing you to create appealing and consistent UI designs. Following the Material Design guidelines, you’re more likely to build apps that look and feel similar to native iOS and Android apps. 

Clean and Readable Code

Consider writing clean and readable code. You can make your code easily understandable and maintainable by employing consistent naming conventions, commenting on your code, and abiding by the best practices. 

Benefits of Using Flutter for App Development

Flutter architecture enables developers and businesses alike to develop groundbreaking applications that perform across platforms. Following are the key benefits of making use of Flutter for your project: 

Single Codebase

Flutter enables you to write a single codebase for both iOS and Android apps, resulting in reduced time, effort, and cost for mobile app development. It allows you to reach a wider pool of audiences without investing massively in developing separate apps for different platforms. 

Customizable Widgets

Flutter comes with a wide library of customizable widgets, easing the creation of unmatched UI designs that stand out. You can also customize the widgets to match your business’s branding and design requirements. It enables you to deliver a tailored user experience. 

Accelerated Development

With Flutter’s hot reload feature, developers can make changes and see them reflected instantly, speeding up the mobile app development process. This allows for rapid experimentation and iteration, which shortens development timelines and enables the creation of high-quality apps faster. 

Enhanced Performance

Flutter architecture is designed to deliver enriched performance, making apps fast and responsive. It results in an enhanced user experience, increased engagement, and retention. 

Ease of Maintenance 

Flutter’s architecture is well-structured, which makes it convenient to update and maintain apps. It minimizes time and resources for ongoing maintenance and lessens the overall development cost. 

Right from a single codebase and customized widgets to accelerated development and excellent performance, Flutter architecture provides numerous benefits to businesses and developers alike.

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When it comes to building apps using Flutter, we’re the one-stop destination for businesses of various sizes. At MindInventory, we’re a team of developers with expertise in Flutter, helping businesses with end-to-end Flutter app development, for example, Ignite and CauliBox.

Ignite is an all-in-one solution for online gym trainers, athletes, as well as owners. The app increased sales by automating email and product liking. Besides, the in-app payments and billings, notifications, and in-app financial metrics helped the owner save time using multiple systems.

CauliBox is London’s first reusable lunchbox scheme with a mission to “Takeaway without the Throwaway. Our solutions helped the client save around 9.75L of water consumption, 237.5g reduction of carbon dioxide emissions per use, and 2.35MJ of energy consumed per use.

If you, too, have an app idea that you want to turn into a groundbreaking Flutter app, we have the solution for you. Right from consulting to design and development, our vetted Flutter app developers will be your ally to bring your ideas to life.

FAQs About Flutter Architecture