Complete Guide to Retrieving Build and Version Numbers in Flutter Apps

Introduction

In mobile app development, particularly during beta testing phases, accurately displaying application version information is crucial for test feedback and issue tracking. The Flutter framework provides convenient methods to retrieve this information, and this article delves into how to use the package_info_plus plugin to achieve this functionality.

Basic Concepts of Version Information

In mobile app development, version information is typically divided into version name and build number. The version name serves as a user-visible identifier, such as "1.0.0", while the build number is used for internal version management, usually as an incrementing number. In Flutter projects, this information can be configured uniformly in the pubspec.yaml file and then mapped to the native configuration files of Android and iOS respectively.

Configuring Dependencies

To use the package_info_plus plugin, you first need to add the dependency in your project's pubspec.yaml file. Open the file and add the following under the dependencies section:

dependencies:
  package_info_plus: ^1.0.6

After adding, run the flutter pub get command to download and install the plugin. Ensure you use the latest version number, which can be checked on pub.dev.

Importing the Package

In the Dart file where you need to use version information, import the package_info_plus package:

import 'package:package_info_plus/package_info_plus.dart';

This step ensures that the classes and methods provided by the plugin are accessible in your code.

Retrieving Version Information

The package_info_plus plugin provides the PackageInfo.fromPlatform() method to retrieve version information. This method returns a PackageInfo object containing properties such as app name, package name, version name, and build number. Depending on the code structure, you can call it asynchronously or synchronously.

Asynchronous Approach

If the calling method is within an asynchronous function, you can use the await keyword:

PackageInfo packageInfo = await PackageInfo.fromPlatform();

String appName = packageInfo.appName;
String packageName = packageInfo.packageName;
String version = packageInfo.version;
String buildNumber = packageInfo.buildNumber;

This approach is suitable for most modern Flutter applications as it avoids blocking the main thread.

Synchronous Approach

If you prefer not to use asynchronous operations, you can handle the returned Future using the then method:

PackageInfo.fromPlatform().then((PackageInfo packageInfo) {
  String appName = packageInfo.appName;
  String packageName = packageInfo.packageName;
  String version = packageInfo.version;
  String buildNumber = packageInfo.buildNumber;
});

This method might be more straightforward in some simple scenarios, but care should be taken to avoid delays during UI construction.

Practical Application Example

Combining with the original query's requirements, here is a complete example demonstrating how to display version information and platform identification in a Flutter app:

import 'package:flutter/material.dart';
import 'package:package_info_plus/package_info_plus.dart';
import 'dart:io';

class VersionDisplay extends StatefulWidget {
  @override
  _VersionDisplayState createState() => _VersionDisplayState();
}

class _VersionDisplayState extends State<VersionDisplay> {
  String version = '';
  String buildNumber = '';

  @override
  void initState() {
    super.initState();
    _loadVersionInfo();
  }

  Future<void> _loadVersionInfo() async {
    PackageInfo packageInfo = await PackageInfo.fromPlatform();
    setState(() {
      version = packageInfo.version;
      buildNumber = packageInfo.buildNumber;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Text('Build: V$version$buildNumber - ${Platform.isIOS ? "iOS" : "Android"}');
  }
}

In this example, we create a stateful Widget that asynchronously loads version information during initialization and dynamically displays it in the UI. Note that we use the Platform class from dart:io to detect the running platform.

Platform-Specific Configuration

The package_info_plus plugin reads version information from each platform's configuration files:

• Android: Information is sourced from the versionCode and versionName fields in the build.gradle file.
• iOS: Information is sourced from the CFBundleVersion field in the Info.plist file.

Ensure that version information is correctly set in these files so that the plugin can read it accurately.

Important Considerations

When using package_info_plus, keep the following points in mind:

• Ensure the plugin version is compatible with the Flutter SDK and update to the latest version regularly.
• In web environments, the plugin's behavior might differ and require additional testing.
• If version information is displayed incorrectly, check if the settings in the native configuration files match those in pubspec.yaml.

Conclusion

With the package_info_plus plugin, Flutter developers can easily retrieve and utilize application version information, which is essential for app testing, release, and user support. The complete examples and detailed explanations provided in this article should help you quickly implement this functionality.