Xcode : ld: library not found for -lXnDDK

After following all of the described steps I get this (last?) error on El Capitan and Xcode:

```
ld: library not found for -lXnDDK
clang: error: linker command failed with exit code 1 (use -v to see invocation)
```

How to solve that?
Am I missing another step?
I didn't find anything else online.
Thanks!
