SwiftPM "swift build" for iOS

still seems to be building for macos despite passing iOS target:

error: the library 'xxx' requires macos 10.13

I could wrap everything is directives to get it to build, but then binary won't include any of my iOS definitions!

#if os(iOS)
@objc public class MediaPlayer : NSObject {

Alternative is to build using xcodebuild

xcodebuild build -scheme RadioPlayerLocal -sdk "`xcrun --sdk iphonesimulator --show-sdk-path`" -destination "OS=17.1,name=iPhone 13 Pro"