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

On 25 Oct 2017, at 9:30 am, Alex Zavatone <zav@...> wrote:

Which version of Xcode?

I haven’t had problems with Xcode 9.0, but 9.0.1 was released and some people are reporting various errors.

Are you using 9.0 or 9.0.1?

On Oct 24, 2017, at 6:22 PM, Graham Cox <graham@...> wrote:

I’m using 8.3.3 ;)

Yes, that was an update! Maybe I should try 9, but somehow an issue like this doesn’t quite seem like an Xcode problem.

—Graham

On 25 Oct 2017, at 9:30 am, Alex Zavatone <zav@...> wrote:

Which version of Xcode?

I haven’t had problems with Xcode 9.0, but 9.0.1 was released and some people are reporting various errors.

Are you using 9.0 or 9.0.1?

On 25 Oct 2017, at 10:45 am, Alex Zavatone <zav@...> wrote:

It sounds like the one of a few things might help.

Look in your "link to binaries” build section to see if any binaries are added twice, or are missing.

Also, check to see in the build file phases that you’re not adding the .m file twice under Compile Sources.

I’ve seen Xcode return an error like this, but really, it was that there were two attempts to build the file with the same methods and it said that it couldn’t link, not that the same file was included twice in the compile process.

I’d check that before attempting to reinstall Xcode 8.3.3.

All looks OK.

I’m going to try Xcode 9, just in case (grasping at straws perhaps). I did upgrade Xcode and the OS separately, but this particular project wasn’t recompiled until now.

—Graham

On 25 Oct 2017, at 10:45 am, Alex Zavatone <zav@...> wrote:

It sounds like the one of a few things might help.

Look in your "link to binaries” build section to see if any binaries are added twice, or are missing.

Also, check to see in the build file phases that you’re not adding the .m file twice under Compile Sources. 

I’ve seen Xcode return an error like this, but really, it was that there were two attempts to build the file with the same methods and it said that it couldn’t link, not that the same file was included twice in the compile process.

I’d check that before attempting to reinstall Xcode 8.3.3.

On 25 Oct 2017, at 12:21 pm, Roland King <rols@...> wrote:

what I usually do to debug these things is pull the link line from the detailed build log, go to the same directory, run it by hand and ensure I see the same result.

Then I start hunting along the command line to ensure the AudioToolbox is really being linked and where it's coming from, then go and check the package to make sure it contains the symbols I need.

You might want (by hand) to also try then shuffling AudioToolbox later in the link line to see if you have a link order issue (CCToneGenerator linked after AudioToolbox). if you can get it going by hand, then go back to Xcode and see what you can do to make it generate a working link line.

On Oct 24, 2017, at 10:17 PM, Graham Cox <graham@...> wrote:

Thanks,

I have managed to get it working, but the reason is something of a mystery.
Xcode 9 showed the same problem, so that wasn’t it. I created a new project and just added the CCToneGenerator class to it (which is where the calls to Audio Toolbox are made). It compiled, linked and worked fine.

I worked through the build settings for each to see what differed. The only one was deployment target - 10.8 for the failing build, 10.13 for the working one. Changing it to 10.13 compiled, linked and worked fine. The earliest deployment target that works is 10.10. This is the mystery - when I previously built this project it targeted 10.8 and that worked fine. The APIs in question are marked as being available from 10.6.

For this project, targeting 10.10 as a minimum is not a problem, but I can’t understand why it can’t target 10.8 as before.

Any ideas?

—Graham

On 25 Oct 2017, at 12:21 pm, Roland King <rols@...> wrote:

what I usually do to debug these things is pull the link line from the detailed build log, go to the same directory, run it by hand and ensure I see the same result.

Then I start hunting along the command line to ensure the AudioToolbox is really being linked and where it's coming from, then go and check the package to make sure it contains the symbols I need.

You might want (by hand) to also try then shuffling AudioToolbox later in the link line to see if you have a link order issue (CCToneGenerator linked after AudioToolbox). if you can get it going by hand, then go back to Xcode and see what you can do to make it generate a working link line.