I tried following this tutorial for setting up metal-cpp with Xcode: https://metaltutorial.com/Setup/. I couldn’t even run the basic hello world project and I get an build failed error saying that <Metal/Metal.hpp> not found for my main.cpp file and <Foundation/Foundation.hpp> not found for my mtl_impl.cpp. The thing is, it was literally working last night. I made 0 changes and it suddenly doesn’t compile. I recreated the project, reloaded xcode, and restarted my computer, no changes.

I’ve checked the search path (both debug and release) and I’ve checked Build Phases > Link Binary with Libraries and they’re all good.