Flutter’s App Lifecycle

The most important and admirable thing you can accomplish while learning Flutter is to have a fundamental understanding of it. Understanding the application lifecycle will help you understand your code, therefore you should always be aware of how an application is generated, rendered, updated, and destroyed. The lifecycle of each application in Flutter is similar to that of every other structure out there.

We will also investigate how to watch an application’s orientation change. We will finally understand how to reuse the lifecycle justification so that all lifecycle strategies are available across our application.

We will examine the Flutter app lifecycle in this blog. We’ll also discuss how to leverage the various application lifecycle strategies that are available in flutter in your own flutter applications.

Flutter’s app Lifecycle

The Flutter App’s lifecycle displays how the application will modify its State. It aids in comprehending the principle underlying the easy development of our applications. Since everything in Flutter is a widget, we should consider Flutter’s widgets before considering its lifecycle.

Two widget categories predominate in Flutter:

  • Stateless Widgets
  • Stateful Widgets

We must understand the differences between the two widgets before considering the Lifecycle.

1. Stateless Widgets

Stateless widgets don’t change significantly throughout the runtime and don’t require dealing with the State. 
Like variables, buttons, symbols, and other things that can’t be modified on the application to recover information, it becomes permanent. 
replaces the build method and then returns widget. When the UI needs the information contained in the actual item, we use it.
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  Widget build(BuildContext context) {
    return Container();

2. Stateful Widgets

Stateful widgets are ones that keep track of the current state and allow for gradual run-time UI changes. Since it is a movable widget, it attracts attention repeatedly over the course of its lifespan.

When the user gradually updates the program screen, we use this. The fact that this widget contains state widgets means that everyone is aware that something has changed on our screen, making it the most important of the many others.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  _MyAppState createState() => _MyAppState();

class _MyAppState extends State<MyApp> {
  Widget build(BuildContext context) {
    return Container();

As a result, since “Stateful Widgets” have to interact with the State, we will concentrate on them as we examine the LifeCycle of Flutter.

Application Lifecycle Stages

The state and its changing characteristics affect the life cycle. A stateful widget contains one so that we can understand how the flutter life cycle is dependent on it. a stage in the life cycle:

  • createState()
  • initState()
  • didChangeDependencies()
  • build()
  • didUpdateWidget()
  • setState()
  • deactivate()
  • dispose()

The life cycle’s stages will be explained in detail now.


When we build another Stateful Widget, this method is invoked. It is a necessary tactic. A case of a State-related with it is returned by the createState() method.

class DemoScreen extends StatefulWidget {

  DemoScreen({Key key}) : super(key: key);
  DemoScreenState<StatefulWidget> createState() => DemoScreen();


This tactic is taken into account when the Widget is created in an engaging manner and is called precisely once for each State object. The initState() method will execute any characterised or added code first, even before the widgets are constructed.

This method must call super.initState(), which executes the parent widget’s initState (Stateful widget). Your variables, objects, streams, AnimationController, and other items can all be initialised here.

void initState(){


When the widget is originally built, this method is invoked after the initState() method. There aren’t many functionalities you can include, such as variable re-initializations and API requests reliant on parent data changes.

void didChangeDependencies() {


This approach serves as the primary technique because it is essential to the rendering of all widgets. Every time we need to display UI Widgets on the screen, it is called.

The Flutter framework alters the build() technique whenever you need to update your UI or, alternatively, on the off chance that you click hot-reload. You can use setState(), which instructs the framework to once more run the form method, if you need to expressly redesign the UI whenever any information is changed.

Widget build(BuildContext context) {
  return Scaffold()


When the Parent widget modifies the configuration in some way, this tactic is used. It basically runs every time we hot reload the programme to check for widget updates.

When a parent widget has to edit a child widget with a comparable Runtime Type because the parent’s properties or designs have changed, didUpdateWidget is triggered. This abandons the new widget and accepts the arrangement modifications made by the previous widget.

void didUpdateWidget(Demo oldWidget) {


The setState() method informs the framework that the object’s internal state has changed in a way that could influence the user interface, allowing the structure to plan a build for this State.

Calling this function after the system has called discard is wrong (). It is crucial to rebuild the UI because this internal state can theoretically affect how the user sees it.

void function(){
  setState(() {});


This approach is taken into account when the State is eliminated from the tree, but it can also be re-inserted into the tree at a different location.

This approach is taken into account when the widget is not yet connected to the Widget Tree but may very likely be added at a later time. The part when you use Navigator is the best example of this. Deactivate is used when a client wants to return to the previous screen after pushing to the next one, in which case the widget will once more be added to the tree.

void deactivate(){


This approach, which is crucial, basically runs counter to the initState() method. It is taken into account when the object and its State ought to be permanently removed from the Widget Tree and won’t ever reassemble.

You can close documents, cancel timers, dispose of animation controls, unsubscribe from streams, and more here. You can ultimately deliver each and every asset in this plan. Currently, if the widget is later added to the widget tree once again, the entire lifespan will be repeated.

void dispose(){


I’ve described the fundamentals of the App Lifecycle in a flutter in the article; you can change the code to suit your preferences. This was a brief introduction from my end to the app life cycle on user interaction, and it functions using Flutter.

I’m hoping that this post will give you enough knowledge to set up the App Lifecycle in your Flutter projects. We’ll demonstrate the Flutter app’s lifecycle for you. This blog post looked at the flutter app’s lifetime. I’m hoping that this blog will better your understanding of the lifecycle. Please give it a try.

I hope this Article has given you some useful knowledge.

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