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Upgrade to V2

This guide shows how to upgrade a project using flutter_rust_bridge V1 to V2.

Concrete commands and checklist​

info

This is just one approach, see below for more approaches.

  • Follow the quickstart to integrate V2 boilerplate into the existing project (in a few commands). Usually, you just need to run flutter_rust_bridge_codegen integrate.
  • Move original Rust code (e.g. in api.rs) to rust/src/api/simple.rs. (You can also split into multiple files, e.g. apple.rs, orange.rs, etc.)
  • Run code generator and watch for code changes by running flutter_rust_bridge_codegen generate --watch.
  • Fix compilation errors (usually just a rename or relocation) and runtime exceptions (usually have hints).
  • Cleanup previous integration of Rust with Flutter by reversing the change done previously, and remove files no longer needed. (See below for an extra checklist)

Alternative approaches​

Details

Surely, there are alternative approaches. For example, if you want to keep the compilation and integration between Rust and Dart, or like to use command line arguments, just find the corresponding counterparts in V2 and rename things.

Changes and quick renames​

Details
  • SyncReturn type becomes annotation: Change fn f() -> SyncReturn<T> {} to #[frb(sync)] fn f() -> T {}
  • api.functionName() -> functionName()
  • DartAbi -> DartDynamic (simple name alias)
  • ZeroCopyBuffer<T> -> T (just remove the wrapper, it is automatically zero-copy by default)
  • Initialize the system via RustLib.init() when starting app.
  • flutter_rust_bridge_codegen -> flutter_rust_bridge_codegen generate
  • flutter_rust_bridge_serve -> flutter_rust_bridge_codegen build-web + standard flutter run (or run in IDE)
  • DartSafe -> simply remove it
  • flutter_rust_bridge::RustOpaque -> crate::frb_generated::RustOpaque (simply moved)
  • flutter_rust_bridge::StreamSink -> crate::frb_generated::StreamSink (simply moved)
  • StreamSink.close -> simply remove it (it is auto closed when the object is dropped)

Some flags are removed, when, for example, they exist mainly for compatibility of later V1 with earlier V1 versions. If you find the removed flag important for your scenario, feel free to create an issue.

Extra checklist for cleanup​

Details
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Here are some concrete possibilities, which may or may not be your own case. This serves to check whether there are missing cleanup steps.

If using this answer​

  • For the iOS setup, you need to reverse the setup steps you did by either removing the old Build Phase (if using method 1) or deleting the script_phase in your Podfile (if using method 2).
  • For the Android setup, you need to reverse your changes to the build.gradle file.

Android​

  • Delete the android/app/src/main/jniLibs/ folder, if this is where the old binaries are stored.

iOS​

  1. Clean up bridge_generated:
    • Delete the ios/Runner/bridge_generated.h file
    • Remove the line #import "bridge_generated.h" in ios/Runner/Runner-Bridging-Header.h
    • Remove bridge_generated.h from the "Copy Bundle Resources" build phase
  2. Delete the ios/Runner/libmyapp.a and remove it from the "Link Binary With Libraries" build phase.
  3. Remove the print("dummy_value=\(dummy_method_to_enforce_bundling())"); line in ios/Runner/AppDelegate.swift if you had that workaround.