Swift compiler error: "non-modular header inside framework module"

Question

Now I would like to migrate my ObjC framework to Swift and I got the following error:

include of non-modular header inside framework module 'SOGraphDB'

The references is to a header file which just define a protocol and I use this header file in some classes to use this protocol.

Is seems related to the module feature but it is at the moment not quite clear how to fix, do you know a solution?

UPDATE:

This is a Swift compiler error.

UPDATE 2:

A quick fix (but not solving the root cause) is to set the following setting to yes: CLANG_ALLOW_NON_MODULAR_INCLUDES_IN_FRAMEWORK_MODULES = YES

Answer 1

Is your header public?

Select the header file in the project explorer. Then in the section on the right in xcode, you'll notice there is a dropdown next to the target. Change that from "project" to "public". This worked for me.