Unity 5.2.2f1 Embed in iOS with extern DllImport("__Internal")] methods fails to compile.

I get the following error:

undefined symbols for architecture arm64:
"_g_PInvokeWrapperPointers", referenced from:
g_CodeRegistration in Il2CppCodeRegistration.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I'm trying to call into Objective-C from Unity, I have the following defined in my MonoBehavior

#if UNITY_IPHONE && !UNITY_EDITOR
[DllImport("__Internal")]
private extern static void ShowNativeDatePicker();
#else
private static void ShowNativeDatePicker() { Debug.Log ("STUB FOR FUTURE");}
#endif

Trying to figure out what I am missing here. Do I need to link anything? Il2CppCodeRegistration.cpp is present and being compiled into the project. I have cleaned my derived data, and cleaned the project and tried to rebuild.

Now it might be that I had my initial project from unity built, then did some work, and went back to test the calls in objective-c after a bit. However, I had already imported the files into the Xcode project and I have not added any additional files after re-building the unity project with my new method added:

[DllImport("__Internal")]
private extern static void ShowNativeDatePicker();

 

Yup, that did the trick.. After rebuilding the app from unity:

1. I just brought the unity/build/path/Classes/ folder back in
2. recompiled and everything works