fix: 'react/utils/FollyConvert.h' file not found

[whiteHatCip]

Description

After upgrading to React Native 0.81.0, an error stating that RCTFollyConvert.h could not be found, I had to handle the error and realized that the file that could not be found had been deprecated, hence, rather than trying to find a way to import that same file, it was the case that the deprecated file had to be ditched in favor of the one that replaces it

Checklist

• I've read CONTRIBUTING.md
• I updated the doc/other generated code with running yarn generate in the root folder
• I have tested the new feature on /example app.
  • In V11 mode/ios
  • In New Architecture mode/ios
  • In V11 mode/android
  • In New Architecture mode/android
• I updated the example app (but no new feature has been implemented)

iOS only Changes

Added RNMBXFollyConvert.h for compatibility

Introduced a new header RNMBXFollyConvert.h that conditionally imports RNMBXFollyConvert.h from the correct location depending on the build configuration (meaning if the user uses use_frameworks! :linkage => :static in their pod file, which is a very common scenario for developers using firebase in their react native apps).

This change was necessary because the import path for react/utils/FollyConvert.h differs when building with or without use_frameworks! (static libs vs modular headers). Some environments also expose legacy or platform-specific paths. By centralizing the conditional imports in a single file, we avoid scattered #if __has_include blocks and ensure consistent, portable compilation across setups. A backward-compatible import is offered for older react-native users that still need to import RCTFollyConvert.h file

[mfazekas]

@whiteHatCip thanks much for looking into this.

So for upgrade I've checked and the diff looks good you made all changes shown by:
https://react-native-community.github.io/upgrade-helper/?from=0.80.2&to=0.81.0

For the RCTFollyConvert.h => FollyConvert.h, which RN versions is that compatible with? And shouldn't we use #import <react/utils/FollyConvert.h>?

[whiteHatCip]

@mfazekas speaking of using

#import <react/utils/FollyConvert.h>

you are totally right, but when I was trying to update my app using a patch-package patch, that import was not working properly, therefore I did fallback to that import using quotes. Now I just updated those imports and the example app is building successfully ✌🏻

And lastly, my own application is having issues when trying to run on android too. Are you experiencing the same issue too?