Setting up CI/CD for a mobile application via CircleCI

CI/CD Setup for Mobile Applications via CircleCI

CircleCI is cloud CI with some of the best macOS runners available among SaaS solutions. For iOS development, speed matters: m2pro.medium executor builds average Swift project in 6–8 minutes. Configuration via .circleci/config.yml, resources stored in CircleCI cloud without managing own servers.

iOS Configuration

version: 2.1

orbs:
  ruby: circleci/[email protected]

executors:
  ios-executor:
    macos:
      xcode: "16.0.0"
    resource_class: m2pro.medium
    environment:
      FASTLANE_SKIP_UPDATE_CHECK: "true"
      BUNDLE_PATH: vendor/bundle

jobs:
  ios-test:
    executor: ios-executor
    steps:
      - checkout
      - ruby/install-deps:
          app-dir: "."
          bundler-version: "2.4.22"
      - restore_cache:
          keys:
            - pods-v2-{{ checksum "Podfile.lock" }}
      - run: bundle exec pod install
      - save_cache:
          key: pods-v2-{{ checksum "Podfile.lock" }}
          paths: [Pods, vendor/bundle]
      - run:
          name: Run tests
          command: bundle exec fastlane test
      - store_test_results:
          path: fastlane/test_output
      - store_artifacts:
          path: fastlane/test_output
          destination: test-results

  ios-deploy:
    executor: ios-executor
    steps:
      - checkout
      - ruby/install-deps
      - restore_cache:
          keys:
            - pods-v2-{{ checksum "Podfile.lock" }}
      - run: bundle exec pod install
      - run:
          name: Deploy to TestFlight
          command: bundle exec fastlane release
          environment:
            MATCH_PASSWORD: ${MATCH_PASSWORD}
            ASC_API_KEY_ID: ${ASC_API_KEY_ID}
            ASC_API_KEY_ISSUER: ${ASC_API_KEY_ISSUER}

workflows:
  ios-workflow:
    jobs:
      - ios-test:
          filters:
            branches:
              only: [main, develop, /feature\/.*/]
      - ios-deploy:
          requires: [ios-test]
          filters:
            branches:
              only: main

Code Signing: Two Approaches

fastlane match (recommended): secret MATCH_PASSWORD added in CircleCI Project Settings → Environment Variables. Each run fastlane match adhoc --readonly fetches profile from Git repository.

CircleCI Contexts: export common variables (MATCH_PASSWORD, Firebase Token) in Context—group of variables shared between projects. Useful for teams with multiple iOS applications.

jobs:
  ios-deploy:
    context:
      - mobile-signing-context

Android in Same config.yml

  android-test:
    docker:
      - image: cimg/android:2024.01
    resource_class: large
    steps:
      - checkout
      - restore_cache:
          keys:
            - gradle-v1-{{ checksum "app/build.gradle" }}
      - run:
          name: Build and test
          command: ./gradlew test assembleRelease
      - save_cache:
          key: gradle-v1-{{ checksum "app/build.gradle" }}
          paths:
            - ~/.gradle/caches
            - ~/.gradle/wrapper
      - store_artifacts:
          path: app/build/outputs/apk/release

Docker image cimg/android:2024.01—official CircleCI Android image with pre-installed Android SDK, JDK 17, Gradle. resource_class: large (4 CPU, 8 GB RAM) needed for Gradle—with medium (2 CPU), build time doubles.

Test Splitting for Long Test Suites

CircleCI supports parallel test execution with automatic distribution by previous run timings:

  ios-test-parallel:
    executor: ios-executor
    parallelism: 4
    steps:
      - checkout
      - run: bundle exec pod install
      - run:
          name: Run tests with splitting
          command: |
            TESTS=$(circleci tests glob "**/*Tests.swift" | circleci tests split --split-by=timings)
            bundle exec fastlane scan --only_testing "$TESTS"

4 parallel containers, each runs ¼ of tests by historical execution time. Total time for 400-test suite reduces from 18 to 6 minutes.

CircleCI iOS Limitations

• No real device access out of box (simulators only). For device testing—Firebase Test Lab integration via CLI
• macOS minute pricing significantly higher than Linux: m2pro.medium ~$0.02/min. With active development—important to limit workflows via triggers

Timeline

Basic CircleCI configuration for iOS (test + deploy): 2–3 days. Full setup with Android, test splitting, Contexts, Slack notifications: 1–1.5 weeks. Cost calculated individually.