This article is based on content originally published on xamarinhelp.com.
Continuous integration and continuous delivery — CI/CD for short — are foundational practices in modern DevOps workflows. For Xamarin mobile developers, implementing CI/CD removes the manual overhead of merging code, running tests, signing binaries, and pushing builds to testers or app stores. This post focuses specifically on the CI/CD pipeline as it applies to Xamarin app development.
What Are CI and CD?
Before diving into implementation, it helps to be clear on terminology:
- Continuous Integration (CI) is the practice of merging all developers’ work into a shared main repository continuously throughout the day. Each merge triggers an automated build and test run, giving developers fast feedback on whether their changes broke anything.
- Continuous Delivery (CD) is the practice of automatically deploying your Xamarin app to testers or end users after a successful build and test cycle, without requiring manual intervention for each release.
Done manually, merging code branches and deploying mobile binaries is time-consuming, tedious, and error-prone. Automating these steps lets your team ship updates faster, catch regressions earlier, and free developers to focus on writing features rather than managing releases.
Continuous Integration for Xamarin
The foundation of any CI workflow is a shared source code repository. Common options for Xamarin teams include GitHub, Bitbucket, and Azure DevOps (formerly VSTS). Every developer pushes their changes to this central repository throughout the day, rather than waiting for periodic, large merges.
But CI is more than just merging source code. A proper CI pipeline for Xamarin apps includes:
- Triggered builds: A build agent starts automatically on each commit or pull request, so problems are caught immediately rather than at the end of a sprint.
- Compilation: The build server compiles the Xamarin iOS and/or Android projects, confirming the code compiles cleanly across all target platforms.
- Unit tests: Automated unit tests run against the shared business logic, verifying correctness without requiring a physical device.
- UI tests: Automated UI tests (for example, using Xamarin.UITest or Appium) validate app behavior on simulators or real devices.
- Failure notifications: If a build or test step fails, the developer who introduced the change is notified immediately.
- Branch protection: Many CI systems can block a pull request from merging into the main branch until all tests pass, preventing broken code from reaching production.
Continuous Delivery for Xamarin
Continuous delivery extends the CI pipeline by automatically packaging, signing, and distributing your Xamarin app once all tests have passed. This is particularly valuable for mobile development, where submitting to the App Store or distributing an IPA/APK to testers manually is a laborious, multi-step process involving certificates, provisioning profiles, and store-specific tooling.
A CD pipeline for Xamarin typically does the following after a successful CI run:
- Builds the release binary: Compiles a release-mode IPA (iOS) or APK/AAB (Android).
- Signs the binary: Applies the appropriate code-signing certificate and provisioning profile automatically, using credentials stored securely in the CI/CD platform.
- Distributes to testers: Uploads the signed binary to a distribution service such as HockeyApp, App Center, or TestFlight, which then pushes it to registered test devices.
- Optionally deploys to production: For the App Store or Google Play, a fully automated submission is possible, though most teams prefer a manual trigger for production releases as a safety gate.
Tools commonly used to automate this process for Xamarin apps include Azure DevOps (VSTS) and Fastlane. Fastlane provides a rich set of actions for building, signing, and deploying iOS and Android apps from the command line, making it a natural fit for CI/CD pipelines running on Linux or macOS build agents.
Choosing a CI/CD Platform for Xamarin
Several platforms support Xamarin CI/CD pipelines out of the box or with minimal configuration:
- Azure DevOps (formerly VSTS): Microsoft’s end-to-end DevOps platform with first-class Xamarin build tasks, integration with App Center for distribution, and support for both self-hosted and Microsoft-hosted build agents (including macOS agents for iOS builds).
- Visual Studio App Center: A Microsoft product that consolidates build, test, distribution, analytics, and crash reporting in a single service. App Center evolved from the earlier HockeyApp and VSTS Mobile Center products; it supports Xamarin directly and connects to GitHub, Bitbucket, or Azure Repos as a source trigger.
- Fastlane: An open-source automation tool particularly strong for iOS signing and App Store submission. It can be integrated into any CI server as a scripted step.
- Jenkins, TeamCity, or Bitrise: General-purpose or mobile-focused CI servers that can be configured with Xamarin and Fastlane tooling.
A Note on HockeyApp and App Center
At the time the original article was written (2017), Microsoft was in the process of consolidating HockeyApp and VSTS Mobile Center into a unified product. That product — Visual Studio App Center — is now the primary Microsoft-recommended platform for mobile CI/CD, crash reporting, and analytics. Developers still using the standalone HockeyApp SDK should review Microsoft’s migration guidance, as the service has since been retired in favor of App Center.
Key Takeaways
- CI for Xamarin means triggering an automated build and test run on every code push to a shared repository.
- CD extends this by automatically signing and distributing the app to testers after every successful CI run, with a manual gate before production releases.
- Automating these steps reduces human error, accelerates feedback loops, and lets developers stay focused on building features.
- Azure DevOps, Visual Studio App Center, and Fastlane are the most commonly used tools in the Xamarin CI/CD ecosystem.
Setting up a solid CI/CD pipeline is one of the highest-leverage investments a Xamarin team can make. The initial configuration effort pays dividends every time a developer pushes code and gets fast, automated feedback — and every time a tester receives a fresh build without anyone manually clicking through a deployment wizard.