Because of our target isolation trick, Xcode is not properly identifying the headers belonging to dependencies, thus having a difficult time handling them. Within a workspace, Xcode will automatically generate the VFS overlays. However, in a single target build, this is not the case. We believe this behaviour is to work around misconfigurations of the builds where some include path points into the product directory while simultaneously referencing headers in the PBXGroup. The overlays help overcome this by matching the headers from the Products to their original source.
Because of our target isolation trick, Xcode is not properly identifying the headers belonging to dependencies, thus having a difficult time handling them. Within a workspace, Xcode will automatically generate the VFS overlays. However, in a single target build, this is not the case. We believe this behaviour is to work around misconfigurations of the builds where some include path points into the product directory while simultaneously referencing headers in the PBXGroup. The overlays help overcome this by matching the headers from the Products to their original source.