Goodday!
Note1: Right-click the target and it is easy to add the search path for header files or lib, but there I havent found any option to add a new source code directory.
Note2: I havnt found an answer in the xcode build documentation for this issue.
P.S.: I hope that I can do it without copying all the files to the xcode explicitly.
Thank you!
Drag the directory containing the files into your Xcode project. The only way Xcode knows it needs to compile the files is if they are contained in the project and a part of the target.