I have a missing framework shown in red in a pod project. The project still builds for running when selecting "Generic iOS Device". However, if I remove the red framework then the project stops building and Xcode reports "Undefined symbols for architecture arm64:" and a big list of symbols not being found by the linker. This is the library which I understand from this SO post has been deprecated and is no longer included in Xcode as of Xcode 10.
I'm currently downloading Xcode 9.4.1 so that I can get the old libraries, but I'm unclear why I can even build successfully when this library is red. Again if I remove it it won't build. As a related aside, the project is already set to use libc++ rather than libstdc++.
Ideas?