Dart/Flutter support for iOS

[lyio]

Language

Dart

FFI Support

• I've validated that the language supports Foreign Function Interface (FFI) bindings

Additional Context

We would like to use Flipt for mobile applications. There already exists a Dart/Flutter client SDK, but that only supports desktop operating systems for now. In #354 I notice that the engine should be available for iOS/Android now.

Can you give some kind of estimation when those might be available in the Dart/Flutter Client SDK?

Willing to Implement

• I'm willing to help implement the Flipt Client SDK in this language if it's accepted. 🙌

Willing to Review

• I'm willing to review contributions to the Flipt Client SDK in this language if it's accepted.

Additional Notes

No response

[markphelps]

Hey @lyio ! Good call, I think theres nothing stopping us from adding ios/android support now to the Dart SDK. I will take a look this afternoon to see how involved it will be and give you an ETA

[markphelps]

@lyio I just released https://pub.dev/packages/flipt_client/versions/0.8.0 which should now work on android. please let me know if it works for you!

[lyio]

@markphelps thanks for the quick update here. I'm afraid that this change is not enough. I'm not sure how this works with plain Dart, but for iOS and Android applications using Flutter the dynamically linked libraries need to be placed in specific directories so that they are properly picked up during the build and included in the assembled applications.

During runtime there is no access to the original file structure of the package. So accessing lib/ffi/flipt.so is not possible at runtime and the initialization fails.

[markphelps]

@lyio Darn. Do you know what these directories are? I am not very familiar with the dart ecosystem

[lyio]

Well, I'm also not quite familiar with the intricacies here. I expected something along the lines of https://docs.flutter.dev/packages-and-plugins/developing-packages#plugin-ffi

But I am not familiar with how the bindings are generated. From what I can see, the actual library files are added to the package right before publishing, so I guess the binaries could be copied to the Flutter specific folders as well.

[markphelps]

awesome. thanks! I think between that and chatgpt I can hopefully get something working

[markphelps]

@lyio I just released v0.9.0-rc.1 that should work for android as I put the libs in android/src/main/jniLibs/

can you try on android and let me know if it works?

i will have to do more work to support ios but will follow up with that

[lyio]

Now, the *.so files are no longer part of the package. AFAIK, pup publish takes the .gitignore into account. So when you

Updated .gitignore to exclude platform-specific directories and binaries (binaries/, android/, ios/, ffi/).

you probably also excluded the binaries from publishing.

[markphelps]

I see the the libraries when I download the release from pub.dev by clicking on the download arrow to get the .tar.gz. Then when I untar it I see the following structure:

flipt_client-0.9.0-rc.1
├── analysis_options.yaml
├── android
│   └── src
│       └── main
│           └── jniLibs
│               ├── arm64-v8a
│               │   └── libfliptengine.so
│               └── x86_64
│                   └── libfliptengine.so
├── build.yaml
├── ffi
│   └── flipt_engine.h
├── ffigen.yaml
├── ios
├── lib
│   ├── flipt_client.dart
│   └── src
│       ├── ffi
│       │   ├── bindings.dart
│       │   ├── loader_flutter.dart
│       │   ├── loader_io.dart
│       │   └── loader.dart
│       ├── flipt_evaluation_client.dart
│       ├── models.dart
│       └── models.g.dart
├── LICENSE
├── native
│   ├── darwin_aarch64
│   │   └── libfliptengine.dylib
│   ├── darwin_x86_64
│   │   └── libfliptengine.dylib
│   ├── linux_aarch64
│   │   └── libfliptengine.so
│   ├── linux_x86_64
│   │   └── libfliptengine.so
│   └── windows_x86_64
│       └── fliptengine.dll
├── pubspec.yaml
├── README.md
└── test
    └── flipt_client_test.dart

19 directories, 23 files

So it seems they are there and should be in the right place according to the docs.

im booting up a sample flutter app and the android emulator locally to test it out

[markphelps]

AH i think you are correct @lyio . I think it was just giving me the source code when i downloaded, not what the actual package would contain.. removing from the gitignore and trying again