InjectionLite Sample Bazel Project

This project demonstrates how to build an iOS SwiftUI application using Bazel with InjectionLite integration for hot reloading during development. You can run this project either from the command line using Bazel directly, or generate an Xcode project for development in Xcode.

Prerequisites

Install Bazel

1. Using Homebrew (Recommended):

   brew install bazel

2. Using the Bazel installer:

   • Download from Bazel releases
   • Follow the installation instructions for macOS

3. Verify installation:

   bazel version

Install Xcode and Command Line Tools

1. Install Xcode from the Mac App Store
2. Install Xcode Command Line Tools:

   xcode-select --install

Getting Started

1. Clone and Navigate to the Project

cd InjectionLiteSampleBazelProject

2. Update Swift Package Dependencies

make update-swift-package-manager

Option 1: Command Line Development (with InjectionNext)

Note: bazel build/run invokes the project wrapper internally; you don't need to call ./tools/bazel directly.

Build the iOS Application

bazel build //:InjectionLiteSampleBazelProjectApp

Run on iOS Simulator

bazel run //:InjectionLiteSampleBazelProjectApp

Development Workflow (Command Line)

1. Build and run the app: bazel run //:InjectionLiteSampleBazelProjectApp
2. The wrapper will auto-launch tools/injection/InjectionNext.app if needed and register the workspace for watching
3. Make changes to Swift files (e.g., ContentView.swift) and save
4. InjectionLite will hot-reload changes in the running app (simulator)

Option 2: Xcode Development

Generate Xcode Project

bazel run //:InjectionLiteSampleProject

This will generate an Xcode project file: InjectionLiteSampleBazelProject.xcodeproj

Open in Xcode

open InjectionLiteSampleBazelProject.xcodeproj

Development Workflow (Xcode)

1. Open the generated Xcode project
2. Select your target device/simulator in Xcode
3. Build and run using Xcode (⌘+R)
4. Make changes to Swift files directly in Xcode
5. Hot reload is NOT supported when running from Xcode in this project
6. Rebuild to see changes when using Xcode

Xcode Project Benefits

• Full Xcode IDE features (autocomplete, debugging, etc.)
• Integrated Interface Builder (if using Storyboards)
• Xcode's built-in iOS Simulator management
• Native Xcode debugging experience
• Access to Xcode's profiling tools

Project Structure

• BUILD - Bazel build configuration defining iOS app target and Xcode project generation
• MODULE.bazel - Bazel module configuration with dependencies (includes rules_xcodeproj)
• Package.swift - Swift Package Manager configuration for InjectionLite
• tools/bazel - Bazel wrapper that auto-starts InjectionNext and registers the workspace when running iOS app targets
• tools/injection/InjectionNext.app - Bundled InjectionNext app used for hot reload
• tools/injection/notify-watch.py - Helper to notify InjectionNext of the project root
• InjectionLiteSampleBazelProject/ - Source code directory
  • InjectionLiteSampleBazelProjectApp.swift - Main app entry point
  • ContentView.swift - SwiftUI view with InjectionLite integration
  • Info.plist - iOS app configuration

InjectionLite Integration

This project includes InjectionLite for hot reloading:

• Linker flags: -interposable flag is configured in the BUILD file
• Dependencies: InjectionLite is imported from the Swift package
• GUI App: InjectionNext.app is bundled at tools/injection/InjectionNext.app
• Auto start: Using bazel run auto-starts InjectionNext (if not running) and registers the workspace for hot reload
• Usage: Save any Swift file while running in debug mode to see changes
• Support: Hot reload is only supported via command-line bazel run; Xcode builds do not support InjectionNext in this project

Configuration

• Port: The wrapper uses port 8887 by default. Override with INJECTION_PORT, e.g. INJECTION_PORT=8888 bazel run //:InjectionLiteSampleBazelProjectApp.

Troubleshooting

Build Issues

• Ensure Xcode Command Line Tools are installed: xcode-select --install
• Clean Bazel cache: bazel clean --expunge
• Update dependencies: make update-swift-package-manager

Missing Headers or Dependency Issues

If you encounter errors like:

• undeclared inclusion(s) in rule
• missing dependency declarations for the following files
• Header files not found
• Swift package dependency resolution failures

Solution:

bazel clean --expunge
make update-swift-package-manager
bazel build //:InjectionLiteSampleBazelProjectApp

The --expunge flag completely removes all build artifacts and cached dependencies, forcing a fresh rebuild that often resolves dependency and header issues.

Target Exclusion or Visibility Issues

If you see errors about targets not being visible or excluded from builds:

• Add visibility = ["//visibility:public"] to your targets in BUILD file
• Run bazel clean --expunge to clear any cached visibility rules
• Regenerate dependencies: make update-swift-package-manager

Permission Issues

If you encounter permission errors for reading or writing files:

• Check file permissions: ls -la
• Ensure your user has read/write access to the project directory
• Run bazel clean --expunge to clear any corrupted cache files
• On macOS, you may need to grant Terminal/IDE access in System Preferences > Security & Privacy

Xcode Project Generation Issues

• If Xcode project generation fails, try: bazel clean --expunge
• Regenerate the project: bazel run //:InjectionLiteSampleProject
• Make sure rules_xcodeproj is properly configured in MODULE.bazel

Simulator Issues

• Make sure you have iOS Simulator installed with Xcode
• Check available simulators: xcrun simctl list devices

InjectionLite Not Working

• Ensure you're running in debug mode
• Check that the -interposable linker flag is present in BUILD file
• Prefer iOS Simulator over physical devices
• Hot reload is not supported when running from Xcode; use bazel run //:InjectionLiteSampleBazelProjectApp
• If you changed the port, ensure INJECTION_PORT matches notify-watch.py second arg

General Recovery Steps

When in doubt, try this sequence:

1. bazel clean --expunge - Completely clean all Bazel artifacts
2. make update-swift-package-manager - Update Swift package dependencies
3. bazel build //:InjectionLiteSampleBazelProjectApp - Rebuild from scratch
4. If using Xcode: bazel run //:InjectionLiteSampleProject - Regenerate Xcode project

Customization

To modify this sample for your own project:

1. Update the bundle_id in BUILD file
2. Change the name in MODULE.bazel
3. Update Swift package dependencies in Package.swift
4. Modify source files in the InjectionLiteSampleBazelProject/ directory

Additional Resources

• Bazel Documentation
• rules_apple Documentation
• rules_xcodeproj Documentation
• InjectionLite GitHub