Expose Objc private headers to Swift in a static library

I need to mix Swift and Objective-C code inside a static library in iOS. I have created module.modulemap file and included the Private module there. I can also import the private module without any error message, but still the compiler throws an error when I try to reference the private class with Use of unresolved identifier 'PrivateClass'

UsePrivateClass.swift

import Foundation
import StaticLib.Private

class UsePrivateClass {
    func printPublicClass() {
        PublicClass().print()
    }
    func printPrivateClass() {
        PrivateClass().print()
    }
}

module.modulemap

module StaticLib {
    export *

    explicit module Private {
        header "PrivateClass.h"
    }
}

I have already set DEFINE_MODULES to YES and MODULEMAP_FILE to the module.modulemap file. Probably missing something related to copying the modulemap file to the right destination or PrivateClass.h header file, but not sure what step is missing.

Created a sample project here.