I want to use some existing C-modules in my new Xcode project. I have compiled them in Xcode with the File-type "Sourcecode.c". After a small work with Macros in this C-File no error are detected anymore and only the "Warning:no rule to process this file ..." is left. After that the Objective-C modules was compiled without any warning, but then the linker did not find the Functions in the C-Module. See in the screenshot. For me it looks like that the C-precopmiler is working but after that the object file is not created. Please help me!