App Versioning and Build Numbers in Flutter: A Comprehensive Guide

11.1.1 App Versioning and Build Numbers

In the world of software development, app versioning and build numbers play a crucial role in the lifecycle of an application. They are not just arbitrary numbers but serve as a communication tool between developers, users, and app stores. In this section, we will delve into the intricacies of app versioning and build numbers, particularly in the context of Flutter development.

Understanding App Versioning

App versioning is a systematic method of assigning unique version numbers to different states of a software application. This practice is essential for several reasons:

• Communicating Updates: Version numbers inform users about updates, bug fixes, and new features, helping them understand the changes in each release.
• App Store Management: App stores rely on version numbers to manage updates and ensure users receive the latest version of an app.
• Tracking and Troubleshooting: Developers use version numbers to track releases, identify issues, and troubleshoot problems effectively.

Purpose of Versioning

Versioning serves multiple purposes in the software development lifecycle:

• User Communication: It provides users with a clear indication of what has changed in the app, whether it’s a major overhaul or a minor bug fix.
• Development Tracking: Developers can track the evolution of the app, making it easier to manage code changes and collaborate with team members.
• App Store Compliance: App stores require version numbers to differentiate between different releases, ensuring users always have access to the latest version.

Semantic Versioning

Semantic Versioning (SemVer) is a widely adopted versioning scheme that conveys meaning about the underlying code changes. It follows a major.minor.patch format:

• Major Version: Incremented for incompatible API changes.
• Minor Version: Incremented when adding functionality in a backward-compatible manner.
• Patch Version: Incremented for backward-compatible bug fixes.

This structured approach helps developers and users understand the nature of changes in each release.

Versioning in Flutter

Flutter manages versioning through the pubspec.yaml file, a central configuration file for Flutter projects. The version is specified in the format major.minor.patch+build.

version: 1.0.0+1

• 1.0.0 represents the version number.
• +1 represents the build number.

Semantic Versioning Breakdown

• Major Version (1): Indicates significant changes that may break backward compatibility.
• Minor Version (0): Represents new features added in a backward-compatible manner.
• Patch Version (0): Denotes bug fixes that do not affect the app’s API.
• Build Number (1): Used for internal tracking and incremented with each release.

Setting Version and Build Number

To set and update version numbers in a Flutter project, follow these steps:

1. Open pubspec.yaml: Locate the version line in your project’s pubspec.yaml file.
2. Update the Version and Build Number: Modify the version and build number as needed.

version: 1.2.3+4

3. Increment Build Number: Ensure the build number is incremented for each release to avoid conflicts on app stores.

Platform-Specific Versioning

Flutter maps versioning to platform-specific configurations for Android and iOS.

Android Versioning

In Android, versioning is mapped to versionCode and versionName in build.gradle.

defaultConfig {
    versionCode flutterVersionCode.toInteger()
    versionName flutterVersionName
}

• versionCode: A unique integer that represents the version of the app.
• versionName: A string that represents the version name shown to users.

iOS Versioning

For iOS, versioning is linked to CFBundleShortVersionString and CFBundleVersion in Info.plist.

<key>CFBundleShortVersionString</key>
<string>$(FLUTTER_BUILD_NAME)</string>
<key>CFBundleVersion</key>
<string>$(FLUTTER_BUILD_NUMBER)</string>

• CFBundleShortVersionString: The version number displayed to users.
• CFBundleVersion: The build number used for internal tracking.

Automating Versioning

Automation can streamline the versioning process, reducing human error and ensuring consistency. Consider using tools and scripts to automate versioning, especially in CI/CD pipelines.

Example Command

Use the --build-name and --build-number flags to automate versioning during the build process:

flutter build apk --build-name=1.2.3 --build-number=4

Best Practices

• Consistency: Ensure version numbers are consistent across all platforms.
• Documentation: Maintain a changelog to record changes made in each version.
• Automation: Use scripts or tools to automate the versioning process.

Visual Aids

Version Number Examples

Version Propagation Flowchart

    graph TD;
	    A[pubspec.yaml] --> B[Flutter Build System];
	    B --> C[Android build.gradle];
	    B --> D[iOS Info.plist];
	    C --> E[versionCode & versionName];
	    D --> F[CFBundleShortVersionString & CFBundleVersion];

Exercise

To solidify your understanding, update the version and build number in a sample Flutter app. Verify that the changes are reflected correctly in the built app by checking the version information on both Android and iOS platforms.

Conclusion

App versioning and build numbers are vital components of the software development lifecycle. They facilitate communication between developers, users, and app stores, ensuring a smooth update process and effective troubleshooting. By following best practices and leveraging automation, you can manage versioning efficiently in your Flutter projects.

Quiz Time!