Duplicate interface declaration for class 'Foo'

Question

I was working on my program, and it seems something in the settings changed. Suddenly I have the error "Duplicate interface declaration for class 'Foo'". It mentions a header file being duplicated but there's only one copy.

Interestingly this is only happening in debug mode, not device mode.

Does anyone have any idea what might be wrong?

I am using Objective-C++ and some static libraries.

Answer 1

I found the problem. There were two copies of the header file and XCode got confused.

Now the mystery is how XCode decided to copy these files by itself ...