What does warning “Mapping architecture arm64 to x86_64” mean?

Question

After migrating my framework to Xcode 10 beta (10L176w) I started to get warnings like:

Mapping architecture arm64 to x86_64. Ensure that this target\

Answer 1

You likely have the VALID_ARCHS ("Valid Architectures") build setting overridden, either for the target or for its project. This is a build setting that should get its value automatically based on which run destination you're building for. When you figure out where this override is coming from (the build setting will display in bold when overridden), select it and hit the delete key to restore it to the default value.