Setup

Dependencies

To start developing your Dart/Flutter library, you will need to download some dependencies locally.

Required

The rest of this guide assumes you have the following tools installed on any development machines:

• Flutter
• rustup
• Melos (needed for our monorepo, see here)
  • dart pub global activate melos to install once Dart/Flutter are installed

Optional

If you would like to build your binaries (for Flutter devices) locally in addition to CI (say, to test on a real device or emulator), you will additionally need the following:

• To compile to macOS/iOS targets
  • macOS
• To cross-compile to Android targets
  • Android NDK
    • Most NDK versions should work nowadays due to fixes in cargo-ndk
      • Previously, NDK version 21 (r21e) was the only one that could be used easily
        • You might see reference to this elsewhere, but that is largely out of date
      • NDK version 25 (r25b) was working at the time of writing this documentation
• To cross-compile to Windows/Linux targets
  • Zig
  • llvm (with clang-cl!)
    • Need to run brew install llvm on macOS since Apple's llvm doesn't have it

Repository Structure

We will be using the following structure for our repository, assuming our library name is library_name:

• .github/ for CI/CD (with GitHub Actions) & dependabot
• packages/ where our Flutter/Dart packages will live
  • library_name/ the Dart-only (library) package using flutter_rust_bridge (FRB)
    • native/ the Rust library used by Dart
    • test/ unit tests for our Dart-only library
    • example/ an example project showing how to use library_name from Dart-only
      • test/ (optional) tests for the example; can be used to ensure example continues to work in CI
  • flutter_library_name/ the Flutter (library) package wrapping around library_name for ease of use
    • android/, ios/, linux/, macos/, & windows/ for platform-specific wrappers in order to bundle our library binaries with Flutter applications
    • test/ unit tests for our Flutter library (note: there might not be any if your Flutter library does not add any Flutter-specific functionality; in that case, add a dummy test in so CI is happy)
    • example/ an example project showing how to use flutter_library_name from within a Flutter application
      • integration_test/ integration tests to ensure your Flutter library, example, and platform-specific configuration are all working together correctly
• scripts/ build Flutter binaries and handle release creation
• platform-build/ the output (build) folder for all created Flutter binaries
• analysis_options.yaml to enable consistent Dart analysis in our Dart/Flutter libraries
• Cargo.toml so IDEs can find our Rust project under packages/library_name/native
• melos.yaml to configure the monorepo, see more here