Objective C example

This example shows how to use ffigen to generate bindings for an Objective C library. It uses the AVFAudio framework to play audio files.

dart play_audio.dart test.mp3

Config notes

The ffigen config for an Objective C library looks very similar to a C library. The most important difference is that you must set language: objc. If you want to filter which interfaces are included you can use the objc-interfaces: option. This works similarly to the other filtering options.

It is recommended that you filter out just about everything you‘re not interested in binding (see the ffigen config in pubspec.yaml). Virtually all Objective C libraries depend on Apple’s internal libraries, which are huge. Filtering can reduce the generated bindings from millions of lines to tens of thousands. You can use the exclude-all-by-default flag, or exclude individual sets of declarations like this:

functions:
  exclude:
    - '.*'
# Same for structs/unions/enums etc.

In this example, we‘re only interested in AVAudioPlayer, so we’ve filtered out everything else. But ffigen will automatically pull in anything referenced by any of the fields or methods of AVAudioPlayer, so we're still able to use NSURL etc to load our audio file.

Generating bindings

At the root of this example (example/objective_c), run:

dart run ffigen --config config.yaml

This will generate avf_audio_bindings.dart.