I've fixed it by reference the project StarstreamSocket, like picture below.

How did you install the lib?
I am also getting the same issue. I have installed the library with carthage. What to do?
In your 'Build Settings' -> 'Swift Compiler - Search Paths' -> 'Import Paths', add the path of the fold 'zlib', for example, $SRCROOT/$PROJECT_NAME/zlib, and then it should work.
I still see the issue on the latest version: 13.1.0
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I still see the issue on the latest version: 13.1.0