import SwiftUI

struct ColorSchemesDemo: View {
  @Environment(\.colorScheme) var scheme
  var body: some View {
    Text(scheme == .dark ? "Scheme: Dark" : "Scheme: Light")
      .padding()
  }
}

                    

import SwiftUI

struct ContentView: View {
  var body: some View { ColorSchemesDemo() }
}

                    

import SwiftUI

@main
struct MyApp: App {
  var body: some Scene {
    WindowGroup { ContentView() }
  }
}