Undefined symbol for architecture armv7: Game Center + Amazon

**Issue:**
I've found multiple people with different versions of this problem but none of them seemed to help. I posted this here because it is only iOS relevant, though my version of the issues seem to arise from the Amazon Game Center libs/plugins I'm using.
Going to the "Link Binaries with Libraries" my GameCenter.a and my AmazonInsightsSDK.a seem to be there and I can't seem to find any .mm files around by these names to add to the Compile sources either. I am building this project from the Unity Game Engine using multiple plugins, though I don't see how that could result in the issue. It could be that I'm not looking for the correct files as well though. I had Game Center working a couple months ago but since I moved back from Android Development, it's been broken.
I've also already tried reinstalling Unity XCode as well as reimporting the latest versions of the plugins in question.

**Error Log:**
Undefined symbols for architecture armv7:
"_OBJC_CLASS_$_CTTelephonyNetworkInfo", referenced from:
objc-class-ref in AmazonInsightsSDK.a(AIIOSDeviceDetails.o)
"__gameCenterIsGameCenterAvailable", referenced from:
RegisterMonoModules() in RegisterMonoModules.o
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

**Used Software:**
I am using Unity 4.3.1f1, XCode 5.0.2, and the latest versions of both Prime31's Game Center Plugin for Unity and Amazons Full Plugin Package for Game Circle and IAP.

Thank you all for your help.

 

It's missing the CTTelephonyNetworkInfo class, which is one of Apple's classes. It is present in the CoreTelephony framework. Is your project linked with it? If not, that's the issue.

 

Thanks a lot!
That fixed my weird Amazon one!
Have any idea about the:

"__gameCenterIsGameCenterAvailable", referenced from:
RegisterMonoModules() in RegisterMonoModules.o

A lot of people are saying that it's an issue where I need to use AppCleaner to remove and reinstall Unity and XCode to fix.

EDIT: Trying the complete removal of Unity and XCode and then reinstalling did not work.

 

Oops, didn't that see that one.

First - you're running on a device, right? Plugins don't usually work in the simulator.

If you're running from the device and the problem is still happening, read on:

Here's what's happening - RegisterMonoModules.cpp is auto-generated by Unity and is used to link function names from C# to C++. What functions? Only the ones that were declared in C# as those that should be called from within C++ (you can look in the C# code for the [DllImport("__Internal")] attribute, that's the one that tells Unity that this function should be linked to the C++ side).

Now, if you're missing that symbol, the most likely scenario is that something went wrong with one of the plugins, probably the GameCenter one. Go into your C# code (which by now must also include the GameCenter plugin's C# code as well) and look for the offending function. How is it declared? Then go into RegisterMonoModules.cpp and see if it's linked there. We shall proceed depending on these investigations.

 

Thanks for being so helpful as well as informative - I like to know what's going on, not just being given the answer.

C#
[DllImport("__Internal")]
private static extern bool _gameCenterIsGameCenterAvailable();

// Checks to see if GameCenter is available on the current device and iOS version
public static bool isGameCenterAvailable()
{
if( Application.platform == RuntimePlatform.IPhonePlayer )
return _gameCenterIsGameCenterAvailable();
return false;
}

C++
This is in the RegisterMonoModules() function:
mono_dl_register_symbol("_gameCenterIsGameCenterAvailable", (void*)_gameCenterIsGameCenterAvailable);
This is the declaration at the top:
void _gameCenterIsGameCenterAvailable();

The function RegisterMonoModules() is called from my main.mm and it has the include for "RegisterMonoModules.h"

The only other place I can find the call in question using basic search is in the Assembly-CSharp-firstpass.dll.s

 

Wow, thanks a lot for the detailed reply Alexey. Helpful and insightful.

I feel like I understand what you're saying, but allow me to make sure: Because of the way the linker does name mangling (what I understand as the forcing of unique naming convention based on some schema - in this case a C based external call) it adds the '_' to the attempted call. But if the original function declaration did not specific this, then when it is linked, it will not be giving the additional '_' and thus the linking fails?

It is to my understanding that extern "C" is c/c++ syntax only. Just in case I tried a few times in my C# script with nothing compilable. So, I'm assuming the extern "C" declaration needs to be added to the C++ functions that my C# script is linking to (what I assume is) XCode/Objective-c.

Correct me at all if I am wrong at all, I'm still a novice with the Objective-C stuff.

My problem is that I haven't a clue where this C++ function/file would be. I am using a Prime31 plugin for my Game Center so I'm not sure if I have any access to their .dll at all. Of course, I could have just been misinformed about the extern "C" in C# or perhaps just attempted it incorrectly when I did.

 

I would have assumed that too, thing is there are a lot of functions exactly like this one (_gameCenterAuthenticateLocalPlayer, _gameCenterIsPlayerAuthenticated, etc.) all being called C# side by a function with the same name but without the leading '_gameCenter'.

Not only that, _gameCenterIsGameCenterAvailable is the only linker error I get in XCode, none of the other ones fail (though this could just be that the linker gives up after the first failure and the rest of them are indeed failing as well)

EDIT: I tried removing the '_' from the C# side with the same error only wiht 1 '_' instead of 2

 

Is _gameCenterIsGameCenterAvailable declared and implemented anywhere in the project? The declaration in RegisterMonoModules is not enough - the linker can't find the implementation.

If it's declared in the GameCenter plugins' headers but is not implemented in any source file, you can dump the symbols of GameCenter.a and see if it's there (probably not, if the linker can't find it).