1. Open Project properties and under Localizations add French to Base and English-Development Language
  2. Add a new file called Localizable.strings using the New File dialog and filtering to Strings File
  3. Right-click the new file, select Show File Inspector and under Localization check both English and French
  4. Two sub-files under Localizable.strings should have appeared

To preview a language in SwiftUI

struct HomeView_Previews: PreviewProvider {
    static var previews: some View {
            .environment(\.locale, .init(identifier: "fr"))