A simple extension to quickly preview dark theme of your view in SwiftUI previews.

SwiftUI Dark Preview

// In your preview struct just add
// `darkThemePreview()` to the view you're previewing!

import SwiftUI

extension View {
    func darkThemePreview() -> some View {
        Group {
            self
            self
                .preferredColorScheme(.dark)
        }
    }
}