macOS Linker error with ExtendedAudioFile

Getting the following linker error

Undefined symbols:
"_ExtAudioFileOpenURL", referenced from:
-[MusicPlay2AppDelegate open:] in MusicPlay2AppDelegate.o
ld: symbol(s) not found
collect2: ld returned 1 exit status

Any ideas? It seems to be finding the header files ok...

Solved!

Had to add the AudioToolbox.framework manually into the project.

How come this is not done automatically when you include header files?