if getting the error “No valid iPhone code signing keys found in keychain” when building your Xamarin IOS project, check that you are building against an ios simulator.
Visual Studio defaults to Device as a build target when creating a new project so this could be what is causing your error.
Change to a simulator instead and try again.
If you do intend to deploy to a Device though, then the error is telling you that you haven’t set up a Device properly.
In order to do that you have to sign up to the Apple developer programme and follow the instructions.