On Oct 24, 2017, at 5:19 PM, Graham Cox <graham@...> wrote:

Hi all,

I’m suddenly running into some linker errors against AudioToolbox on a project after upgrading Xcode and installing High Sierra (not sure which of these did it).

Undefined symbols for architecture x86_64:
"_AudioComponentFindNext", referenced from:
-[CCToneGenerator createToneUnit] in CCToneGenerator.o
"_AudioComponentInstanceDispose", referenced from:
-[CCToneGenerator dealloc] in CCToneGenerator.o
"_AudioComponentInstanceNew", referenced from:
-[CCToneGenerator createToneUnit] in CCToneGenerator.o
"_AudioOutputUnitStart", referenced from:
-[CCToneGenerator setEnabled:] in CCToneGenerator.o
"_AudioOutputUnitStop", referenced from:
-[CCToneGenerator stop] in CCToneGenerator.o
"_AudioUnitInitialize", referenced from:
-[CCToneGenerator setEnabled:] in CCToneGenerator.o
"_AudioUnitSetProperty", referenced from:
-[CCToneGenerator createToneUnit] in CCToneGenerator.o
"_AudioUnitUninitialize", referenced from:
-[CCToneGenerator stop] in CCToneGenerator.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I’m linking against AudioToolbox, the source code includes the headers and the ‘Jump to Definition’ finds the declaration in the header OK. The functions are not deprecated and the project built just fine last time I tried it (which was some months ago on a different Xcode/OS version). When building the project, Xcode did not prompt to update any build settings as it usually does after an update.

Any ideas what could be causing this?


—Graham