ReactBrownfield code duplicates

[pastwamichal]

Hello, recently we have made a POC with some basic functionality done in React Native and integrated it into a native app. All 3 frameworks generated by rock (hermes, ReactBrownfield and MyFramework) were added to the app target as embedded frameworks.

Right after running the app I saw these warnings in the console:

objc[1061]: Class PodsDummy_ReactBrownfield is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cede68) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922f7f8). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.
objc[1061]: Class ReactNativeBrownfieldModule is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cedeb8) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922f848). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.
objc[1061]: Class _TtC15ReactBrownfield29ReactNativeBrownfieldDelegate is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cedf40) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922f8d0). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.
objc[1061]: Class _TtC15ReactBrownfield21ReactNativeBrownfield is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cee050) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922f9e0). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.
objc[1061]: Class _TtC15ReactBrownfield31ReactNativeBrownfieldModuleImpl is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cee228) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922fbb8). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.
objc[1061]: Class _TtC15ReactBrownfield25ReactNativeViewController is implemented in both /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Frameworks/MyFramework.framework/MyFramework (0x106cee2d8) and /private/var/containers/Bundle/Application/BC5CFCFE-487D-409F-A41E-E3E493EB45BA/Test.app/Test.debug.dylib (0x10922fc68). This may cause spurious casting failures and mysterious crashes. One of the duplicates must be removed or renamed.

Duplicated classes come from ReactBrownfield framework. I used nm command to investigate internals of MyFramework and it looked like it already contained the code from ReactBrownfield.
For example, these symbols are related to ReactNativeViewController:

00000000004a37c8 s __INSTANCE_METHODS__TtC15ReactBrownfield25ReactNativeViewController
00000000006a06d8 s __IVARS__TtC15ReactBrownfield25ReactNativeViewController
00000000006a0690 s __METACLASS_DATA__TtC15ReactBrownfield25ReactNativeViewController
00000000006c62d8 S _OBJC_CLASS_$__TtC15ReactBrownfield25ReactNativeViewController
00000000006cddd8 D _OBJC_METACLASS_$__TtC15ReactBrownfield25ReactNativeViewController
00000000006c6278 s __DATA__TtC15ReactBrownfield25ReactNativeViewController

However, after removing ReactBrownfield from app's dependencies I got a compilation error Unable to find module dependency: 'ReactBrownfield' on line @_exported import ReactBrownfield in arm64-apple-ios.private.swiftinterface inside MyFramework. Apparently ReactBrownfield is needed for exposing public interface.

What I also found is that both hermes and MyFramework are dynamic frameworks, while ReactBrownfield is a static framework, which might explain this behaviour.

I also tried wrapping these frameworks in one SPM package, but the result is the same.

Am I doing something wrong with my setup, or is it an issue with generating frameworks? If ReactBrownfield is a static framework, then maybe it should be compiled into MyFramework and not required in the project? Or maybe it should be dynamic and not compiled into MyFramework?

Thank you for any suggestions or help :)

[tlomozik]

Hi! Any updates on this? 🙏

[thymikee]

Do these warnings prevent the app from running?

[pastwamichal]

@thymikee no, the app works fine and the framework provides the functionality as intended. In my case I did not see any runtime issues.
Nevertheless, duplicated code may lead to some unexpected issues (like spurious casting failures as the warning states). Hard to say how much of a problem it is in this particular case, though.

[thymikee]

Great to hear it's working then! I'll keep the issue open as an improvement opportunity. Feel free to tackle it and send a PR here or to the react-native-brownfield project :)

[MrZJB]

How was it solved? I also encountered this problem

[MrZJB]

To be exact, debugging an application on a simulator is normal, but it will directly Crash when running on a real machine.

[pastwamichal]

@MrZJB It was not solved, code duplicates are likely created by the tool when building xcframeworks.
We did encounter some crashes at first, but they were caused by missing window: UIWindow? reference in AppDelegate. After fixing that, we did not see any more issues.
What exception do you get? If it works on simulator but immediately crashes on the device, then it is likely that frameworks were not embedded in the app. Linking dynamic frameworks works differently for simulators and devices, as simulators run on the same device and they do not need to be embedded to work. Make sure you added all frameworks to "Frameworks, Libraries, and Embedded Content" under "General" tab in the project settings and set them to "Embed & Sign", as shown on this video https://www.youtube.com/watch?v=siA6LuGxaAI.

[MrZJB]

@MrZJB问题尚未解决，代码重复可能是工具在构建时生成的xcframework。 我们最初确实遇到了一些崩溃，但那是由于缺少window: UIWindow?引用导致的AppDelegate。修复后，我们没有再遇到任何问题。 您遇到了什么异常？如果在模拟器上运行正常，但在真机上立即崩溃，则可能是框架没有嵌入到应用程序中。动态框架的链接方式在模拟器和真机上有所不同，因为模拟器运行在同一设备上，无需嵌入即可工作。请确保已将所有框架添加到项目设置中“常规”选项卡下的“框架、库和嵌入内容”中，并将其设置为“嵌入并签名”，如本视频所示：https://www.youtube.com/watch?v =siA6LuGxaAI 。

Exactly, the problem I had was
objc[4656]: Class _TtC15ReactBrownfield21ReactNativeBrownfield is implemented in both /private/var/containers/Bundle/Application/4F20F665-2A73-4AC5-A445-0B9288758F6B/NativeIOSExample.app/Frameworks/RN_Demo_VersionReact.framework/RN_Demo_VersionReact (0x102ec4100) and /private/var/containers/Bundle/Application/4F20F665-2A73-4AC5-A445-0B9288758F6B/NativeIOSExample.app/NativeIOSExample.debug.dylib (0x1008cd028). One of the two will be used. Which one is undefined.
objc[4656]: Class _TtC15ReactBrownfield25ReactNativeViewController is implemented in both /private/var/containers/Bundle/Application/4F20F665-2A73-4AC5-A445-0B9288758F6B/NativeIOSExample.app/Frameworks/RN_Demo_VersionReact.framework/RN_Demo_VersionReact (0x102ec4350) and /private/var/containers/Bundle/Application/4F20F665-2A73-4AC5-A445-0B9288758F6B/NativeIOSExample.app/NativeIOSExample.debug.dylib (0x1008cd1c8). One of the two will be used. Which one is undefined.