To add files to your generic iOS library make sure the header file you want to include is in the target header section. Like this.
Note – if you click on the headers section and you don’t see the class you want to add, try dragging it from the left project area into the header section. Thank you Johan.
If you get linker errors like this
Add the offending file *.m to the compile build phase.
Drag it over from the left into Compile Sources. Then try again. It should work.
Linking error in library
If you get an error in your core library passes the build but fails when you run the tests
Check your test build scheme and verify that you don’t have the file added here also. It should only be added to one build scheme – probably the project. But not both.
Can’t find header
Remember that when you add a new file to the sublibrary, you need to add it to the public headers of the sublibrary.