How to add some Check on Resume (return to your App) in Flutter

To add a Check in Flutter when an App executes Resume  from a background or terminated state, you can use the WidgetsBinding class’s addObserver method to listen for the LifecycleState changes. Here are some steps you can follow:

1. Create a class that extends WidgetsBindingObserver:
   This is where you’ll put your resume logic. You can add checks and perform actions when the app resumes.
2. Add observer to WidgetsBinding:
   In your widget’s build method, add the observer.

Here is an example:

import 'package:flutter/material.dart';
import 'package:flutter/services.dart' show SystemChrome.setPreferredOrientations;
import 'package:flutter/widgets.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    switch (state) {
      case AppLifecycleState.resumed:
        // Resume logic here
        print('App resumed');
        break;
      case AppLifecycleState.paused:
        // Pause logic here
        print('App paused');
        break;
      case AppLifecycleState.detached:
        // Detach logic here
        print('App detached');
        break;
      case AppLifecycleState.inactive:
        // Inactive logic here
        print('App inactive');
        break;
// not present anymore in the api      case AppLifecycleState.unknown

case AppLifecycleState.hidden:

       // Unknown logic here
        print('App hidden');
        break;
    }
  }

  @override
  void didChangeMetrics() {
    super.didChangeMetrics();
    // Metrics change logic here
  }

  @override
  void didChangeLocales() {
    super.didChangeLocales();
    // Locales change logic here
  }

  @override
  void didChangePlatformBrightness() {
    super.didChangePlatformBrightness();
    // Brightness change logic here
  }

  @override
  void didUpdateWidget(MyHomePage oldWidget) {
    super.didUpdateWidget(oldWidget);
    // Update widget logic here
  }

  @override
  void didUpdateWidget(MyHomePage oldWidget) {
    super.didUpdateWidget(oldWidget);
    // Update widget logic here
  }

  @override
  void dispose() {
    super.dispose();
  }
}

In the above code, didChangeAppLifecycleState is where you’ll put your resume logic. This method gets called when the app’s lifecycle state changes.

Note: Don’t forget to remove the observer in dispose method when your widget is removed from the tree.

Example use case:

You can add checks and perform actions when the app resumes, such as:

• Checking if there are any new notifications
• Fetching data from the server to update your app’s state
• Showing a welcome message or tutorial when the user resumes the app after a long time

@override
void didChangeAppLifecycleState(AppLifecycleState state) {
  switch (state) {
    case AppLifecycleState.resumed:
      // Fetch data from server to update app's state
      fetchAndUpdateData();
      break;
  }
}

void fetchAndUpdateData() async {
  // Fetch data from server
  final data = await fetchDataFromServer();

  // Update app's state with the fetched data
  setState(() {
    // Update your widget's state here
  });
}

Very obvious example where resume check may be needed is when your app requires some permissions. https://programtom.com/dev/2025/01/22/example-of-how-to-use-the-permission_handler-package-in-flutter/. Both iOS and Android users may pause your app, remove the permissions and return, resulting in a situation – where the app cannot complete the functionality it is programmed to. So, is is always good idea to program defensively.