Module compiled with Swift 5.0.1 cannot be imported by the Swift 5.1 compiler

Question

I have a VoiceSampler.framework that was built with Xcode 10.3

I am trying to use that framework in Xcode11 in a new project. I have successfully added that framewor

Answer 1

You need to set the Build Libraries for Distribution option to Yes in your framework's build settings, otherwise the swift compiler doesn't generate the necessary .swiftinterface files which are the key to future compilers being able to load your old library.

This ends up in your project.pbxproj file as:

BUILD_LIBRARY_FOR_DISTRIBUTION = YES;

After setting this flag, a framework I compiled using Xcode 11.0 (swift 5.1) was able to be compiled with Xcode 11.2 (swift 5.1.2) and everything appears to be working correctly.