How to preview your layout in light and dark mode

Most of Apple’s operating systems support both light and dark mode user interfaces, so it’s no surprise that SwiftUI has support for this functionality built right in.

Even better, once you’ve designed your interface Xcode allows you to preview your layouts in either color scheme by setting the \.colorScheme environment value in your preview.

For example, this shows a preview using dark mode:

#if DEBUG
struct ContentView_Previews : PreviewProvider {
   static var previews: some View {
      Group {
         ContentView()
            .environment(\.colorScheme, .dark)
      }
   }
}
#endif

If you want to see both light and dark mode side by side, place multiple previews in a group, like this:

#if DEBUG
struct ContentView_Previews : PreviewProvider {
   static var previews: some View {
      Group {
         ContentView()
            .environment(\.colorScheme, .light)

         ContentView()
            .environment(\.colorScheme, .dark)
      }
   }
}
#endif

Tip: If your preview is zoomed right in, you should either scroll around or zoom out to the other previews.