I simply opened arboreus_examples/qt6/CMake/UsingSwift/UsingSwift_v3/CMakeLists.txt in QT Creator and was able to build it and run.

In its main.cpp it creates a Swift wrapper and calls method:

ASwift* oSwift = new ASwift(&oEngine);
oSwift->mInit();
_A_DEBUG << oSwift->mString();