GenericUIViewControllerRepresentable.swift

import SwiftUI

struct GenericUIViewControllerRepresentable<ViewControllerType>: UIViewControllerRepresentable
    where ViewControllerType: UIViewController {
    
    let factory: (Context) -> ViewControllerType
    
    func makeUIViewController(context: Context) -> ViewControllerType {
        factory(context)
    }
    
    func updateUIViewController(
        _ uiViewController: ViewControllerType,
        context: Context
    ) {}
}

Usage:

struct ViewController_Preview: PreviewProvider {
    static var previews: some View {
        GenericUIViewControllerRepresentable { _ in
            return ViewController()
        }
    }
}

For old legacy code add:

#if canImport(SwiftUI) && DEBUG
.
.
.
#endif

• also:

#if canImport(SwiftUI) && DEBUG
import SwiftUI

let deviceNames: [String] = [
    "iPhone SE",
    "iPhone 11 Pro Max"
]

struct ViewController_Preview: PreviewProvider {
    static var previews: some View {
        ForEach(deviceNames, id: \.self) { deviceName in
            GenericUIViewControllerRepresentable { _ in
                ViewController()
            }
            .previewDevice(PreviewDevice(rawValue: deviceName))
            .previewDisplayName(deviceName)
        }
    }
}
#endif