Recently I ran into an error when trying to run a SwiftUI Project on my iPhone. I'm running this project on a M1 Macbook Pro. The error seemed to start happening when my project started using certain Cocoapods. The error reads "ARCHS[@]: unbound variable".
To fix this error all you need to do is navigate to the Project File > Info > Excluded Architecture. If in Excluded Architecture you see arm64, all you need to do is remove the arm64 and reload your Xcode project.
Hope this quick post helps anyone struggling with this weird error in your SwiftUI project. If this doesn't help please check out this stack overflow post.