[Crashlytics] Fix missing Swift header error

[ncooke3]

One reason that I think we did not see this issue with Sessions and CoreInternal is because we never tried to import generated Swift header within the module is belonged to:

git grep '\-Swift.h' ':!**/*Test*/**' ':!Crashlytics/*'  ':**/*.[hm]'
CoreOnly/Sources/Firebase.h:    #import <FirebaseFunctions/FirebaseFunctions-Swift.h>
CoreOnly/Sources/Firebase.h:    #import <FirebaseStorage/FirebaseStorage-Swift.h>

When use_frameworks! isn't used, <*/*-Swift.h> can't be resolved since the <...> syntax looks for a framework. But, the -Swift.h is still generated in the build directory. The header is findable by a header search path (potentially set by CocoaPods) in the build products directory so we can just import the header directory (e.g. "*-Swift.h").

To test, I created a Podfile that depended on FirebaseCrashlytics, 10.23.0 and had use_modular_headers!. This reproduced the problem. Then I verified that importing the header without the framework notation worked.

[paulb777]

Nice!

Can you add --use-modular-headers to the pod lib lint matrix in CI?

[themiswang]

Thank you for helping on this!

[haozhutw]

I tried again with 10.23.0 and changed<FirebaseCrashlytics/FirebaseCrashlytics-Swift.h> to <FirebaseCrashlytics-Swift.h>, it did work. My podfile also contains use_modular_headers! . I'll wait for a new release, thank you all!