Import third party C library into swift causes err

Question

This question is a continuation of a previous one I'm currently migrating this (https://github.com/emilwojtaszek/leveldb-swift) library from swift 2 to swift 3/4. Here is the link to my fork https://github.com/lu4/leveldb-swift/tree/MigrationFromSwift2ToSwift3 (please note that the target branch is MigrationFromSwift2ToSwift3)

I was able to resolve (with many thanks to @Ruslan Serebriakov) all of the issues with initial code base and check that the code is running.

However after trying to update LevelDB C code to latest master I got new type of error which I don't understand how to resolve:

Include of non-modular header inside framework module 'LevelDB.c': '/Path/to/Project/leveldb-swift-migration/vendor/leveldb/include/leveldb/export.h'

I've did some research on the internet but the issues described there seem non-related with one I've stumbled on. Here is an image of the issue

Any help is appreciated, thank you in advance!

Answer 1

I'm never 100% certain with mixed language frameworks. But an error like this happens in Swift projects when:

• since you cannot use a Bridging Header in frameworks,
• you #import a C header in the Foo-Framework.h to expose it so the Swift code, and
• the header is not itself marked "Public" to the target.

"Non-modular" seems to indicate "not part of the published module interface". At least with Swift--C mixes, you can only combine both through making the C headers public; no way to import private header files there, which is weird.

Give it a shot: Since you are obviously importing the file in non-Swift code, try to locate the export.h header file in your Xcode project, open the File inspector (⌘⌥1), and ensure public visibility in the framework target: