I have created a swift (iOS/MacOS) library on CocoaPods (BillboardSwiftLibrary). Generally, it has its assets and Classes folders which contain the source files.
I want my library to support Swift Package Manager, so I moved the source files from the Classes folder into a Sources folder outside the pod. However, they are still accessible from the Development pods.
Now my library won't build for Cocoapods launch but compiles for Swift Package Manager, I get the error below when I run pod lib lint BillboardSwiftLibrary.podspec
ERROR | file patterns: The source_files pattern did not match any file.
From @Larme's comment, I found the answer.
In your podspec file, change the location of your classes to the sources folder.
So changed my s.source_files from to BillboardSwiftLibrary/Classes/**/*
to Sources/**/*
and pod lib lint BillboardSwiftLibrary.podspec
worked fine.