Summary:
Using Fabric with a Swift native module is currently broken. There are currently two issues.
If you try to integrate a native module with Swift code, you will get the following error when running `pod install` with Fabric enabled:
```
[!] The following Swift pods cannot yet be integrated as static libraries:
The Swift pod `MyNativeView` depends upon `React-RCTFabric`, `React-Codegen`, `RCTTypeSafety`, and `ReactCommon`, which do not define modules.
To opt into those targets generating module maps (which is necessary to import them from Swift when building as static libraries),
you may set `use_modular_headers!` globally in your Podfile, or specify `:modular_headers => true` for particular dependencies.
```
To resolve this, I have applied the suggestion from the error (set `:modular_headers => true` for the appropriate modules inside `react_native_pods.rb`.
Afterwards, `pod install` succeeds but I still got `Redefinition of module 'React'` during the build due to the conflict inside the generated modulesmaps `React-Core.modulemap` and `React-RCTFabric.modulemap`. This makes sense since `React-RCTFabric.podspec` has `s.header_dir = "React"` (see [here](https://github.com/facebook/react-native/blob/main/React/React-RCTFabric.podspec#L37)) and the module inherits that. However, we can explicitly specify `module_name` for the podspec which is what I have done. I have named the module `Fabric`, let me know if you think there's a better name.
## Changelog
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[iOS] [Fixed] - Fix using Swift in a native module with Fabric enabled
Pull Request resolved: https://github.com/facebook/react-native/pull/33743
Test Plan:
1. Clone [this](https://github.com/fortmarek/react-native) repo
2. From `main`, apply changes from [this](26958fccf4) commit (adding Swift file to the `MyNativeView` native module in the RN tester app)
3. Try to run `USE_FABRIC=1 RCT_NEW_ARCH_ENABLED=1 USE_CODEGEN_DISCOVERY=1 USE_HERMES=0 bundle exec pod install` inside the `packages/rn-tester`
4. Observe errors
5. Apply [the commit](9772c6209d) from this PR
6. Both pod install and the subsequent build should succeed.
I can also make changes to the current `MyNativeView` module to include Swift as well if it's something that the React Native Core team would be interested in - in case you want the Swift native modules to be always buildable on `main`
Reviewed By: dmitryrykun
Differential Revision: D36097852
Pulled By: cipolleschi
fbshipit-source-id: 2faebcffd1115339f89a406e265a6a040218dc9c
709a459b1e