Possible codegen/link problems

We have a complex Objective C++/C++ project that uses, among other things OpenCV's cvflann kdtree implementation.

I'm not sure if this is the right list to inquire on. But we're having a really hard time figuring this out. Xcode 9's debugging is leaving a lot to be desired (can't single-step assembly instructions, can't view memory pointed to by registers, etc.)

We're willing to pay someone for their time to help figure this out. I need an expert in x86/ARM generated code, iOS ABI, C++ templates, etc.