With the help of a this Flutter plugin. *Check if a user has the most recent installation of your app. *Display a message to the user with a link to the relevant app store page.
See more at the Dart Packages page.
Add new_version as a dependency in your pubspec.yaml file.
dependencies:
new_version: ^0.3.0
Create an instance of AppUpdate in main.dart (or wherever your app is initialised).
final appUpdate = AppUpdate();
Your Flutter package identification will be used by the plugin automatically to search the app store. You can overwrite this identity if your app uses a different one on the Google Play Store or Apple App Store by giving values for androidPackageName and/or iosPackageName.
For iOS: You must specify iOSAppStoreCountry to the two-letter country code of the Software Store you want to search if your app is only accessible outside the India. A list of ISO Country Codes can be found at http://en.wikipedia.org/wiki/ISO 3166-1 alpha-2.
Calling showUpdateAlert with your app's BuildContext will check if the app can be updated, and will automatically display a platform-specific alert that the user can use to go to the app store.
appUpdate.showUpdateAlert(context: context);
"# app_update"