HasAttributeContentView.swift

import SwiftUI

#if hasAttribute(dynamicMemberLookup)
@dynamicMemberLookup
struct Print {
    static subscript(dynamicMember member: String) -> String {
        print(member)
        return member
    }
}
struct ContentView: View {
    @State var input = ""
    @State var output = ""
    var body: some View {
        Form {
            Button("Print") {
                output = Print.helloWorld
            }
            Text(output)
        }
    }
}
#endif