Flutter is a free, open-source mobile user interface (UI) framework that Google developed in 2017. It allows users to create native mobile applications using a single codebase. Using a single codebase and one programming language, users can develop apps for two different platforms, Android and iOS. It’s considered the most effective cross-platform framework available.
Flutter is all about widgets, and these widgets can be classified into two categories, stateless and stateful widgets. A stateless device does not have any internal state, i.e. once the widget is built, it cannot be changed or modified until it is initialized again. On the other hand, a stateful widget is dynamic and has a state, i.e. it can be modified easily throughout its lifecycle without initializing it.
A state is a piece of information that can be read when the widget is built and can be changed or modified during the lifetime of an app. State management is one of the most popular and essential processes in an app’s lifecycle. Since Flutter is declarative, Flutter builds its UI by reflecting the current state of an app. State management centralizes all the forms of various UI controls to handle data flow across the application.
For example, a “welcome” message must be shown upon opening the app, but not on any subsequent page visits; a user state is required. Managing the state of an application is vital and is what the application knows about the user, where the user is located, the information that has been entered, and also the status of UI controls after the user has entered the information.
Regardless of the changes in user state, Flutter state management libraries makes it easy to build and manage apps. Developers can design UI from scratch using Flutter’s declarative programming style, which reflects the app state as per user interface.
Popular Flutter State Management Libraries
A state management library is a good option when developing a complex Flutter app. To return changes to an application state, Flutter uses a declarative programming structure. Some of the popular Flutter state management libraries are:
- BLoC: BLoC or Business Logic Component, is recommended by Google and is one of the most popular approaches. BLoC enables the separation of Flutter application logic into a single component, the Business Logic Component. BloCs are usually assigned to every screen in a Flutter application, which helps separate the presentation code from the business logic, making it easier to test and reuse. It enables developers to work on the same code base using uniform patterns and conventions.
- InheritedWidget: InheritedWidget is another state management solution offered by Flutter and it’s a special type of widget that helps define the context of the root at the base tree. The advantage of this is that the lowest widget at the sub-tree can directly access the state defined in InheritedWidget without affecting other widgets residing above it. It allows developers to create a widget that other widgets can inherit in an app. Therefore any changes made in this inherited widget are automatically propagated down to the child widgets. The primary advantage of InheritedWidget is that it’s easy to understand and use, but can be difficult to manage when the app becomes more complex.
- Provider: Provider state management allows for a simple and efficient way to access and modify an application’s state from anywhere in the code. The Provider class in the BLoC package can access objects of the widget tree. The Provider can also be used with Triple, ValueNotifier, ChangeNotifier and other state objects. The Provider Pattern is well known for managing state in Flutter applications and is highly recommended for simple projects which need to manage state in a more maintainable way.
- River pod: Riverpod is a new entrant in state management solutions for Flutter and builds on top of the Provider Pattern. Riverpod is an implementation of InheritedWidget from scratch. In Riverpod, InheritedWidget is implemented easily and simply. Riverpod can identify coding errors during compilation, and this unidirectional data flow makes apps more scalable as app objects are made visible in Flutter’s dev tool by default. It also simplifies complex object graphs and makes patterns independent of Flutter.
- MobX: MobX offers a simple way to connect reactive data to the user interface. It’s based on three main concepts – Observables, Actions and Reactions. The reactive data is easily connected to the UI through a state management library. Its design makes state management very easy by reactively detecting all the changes and propagating those to the required UI. It automatically tracks what is being used or consumed, known as observables. The key feature is that all changes are automatically tracked in the observables without any explicit connections. Developers need not worry about keeping the UI and data in sync.
- GetX: GetX is an extra-light and powerful state management solution for Flutter and combines route management, state management, navigation and intelligent dependency injection. It offers complete decoupling of View, presentation logic, dependency injection and business logic. It is one the easiest, practical, secure and scalable way to build applications with Flutter, offering a wide range of APIs and features for developers to build apps faster. The dependency injection feature makes app development easier as developers don’t need to depend on context, route, or widget tree.
- Cube: The Cube library uses dependency injection with the need for code generation. It objectively simplifies state management and minimizes the code complexity by rebuilding the widget tree as needed. Object-oriented state management is the application’s focus, reducing the coding complexity.
Besides these state management libraries, some other libraries are:
There is no definitive guide to deciding what to use and when. State management use depends on the application and its developers. Each technique has its pros and cons. The Flutter community is constantly evolving, and there will be many changes, additions, and deletions. Flutter’s growth can be attributed to its capability to create fast and attractive user experiences for the web, mobile and desktop using a single codebase. Using Flutter application development services to design and develop apps can help add value to app development for any business.