SwiftUI PreviewProvider generic function for previews?

Question

In each view I have a similar code block. Would it be possible to pass the view as a parameter? I would like to be able to pass HomeViewDemo(), MainView() or AccountView() as a parameter for the function to generate the simulations of that view for each device.

struct HomeViewDemo_Previews: PreviewProvider {
    static var previews: some View {
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize0))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize0)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize1))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize1)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize2))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize2)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize3))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize3)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize4))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize4)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize5))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize5)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize6))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize6)
        
        HomeViewDemo()
            .previewDevice(PreviewDevice(rawValue: WPDevice.Phone.name.iPnoneSize7))
            .previewDisplayName(WPDevice.Phone.description.iPnoneSize7)
    }
}

Answer 1

I have solved this by defining a config struct:

struct PreviewConfig: Identifiable {

    enum Size {
        case smallest
        case averge
        case largest
    }

    let size: Size
    let colorScheme: ColorScheme
    let sizeCategory: ContentSizeCategory
    let displayName: String
    let id = UUID()

    var device: PreviewDevice {
        switch size {
        case .smallest:
            return PreviewDevice(rawValue: "iPhone SE (1st generation)")
        case .averge:
            return PreviewDevice(rawValue: "iPhone 11 Pro")
        case .largest:
            return PreviewDevice(rawValue: "iPhone 14 Pro Max")
        }
    }
}

I also have an Array with my most commonly used ones:

extension Array where Element == PreviewConfig {

    static let core = [
        PreviewConfig(
            size: .averge,
            colorScheme: .light,
            sizeCategory: .large,
            displayName: "Average iPhone"),
        PreviewConfig(
            size: .averge,
            colorScheme: .dark,
            sizeCategory: .large,
            displayName: "Average iPhone - dark mode"),
        PreviewConfig(
            size: .averge,
            colorScheme: .light,
            sizeCategory: .extraExtraLarge,
            displayName: "Average iPhone - large font"),
        PreviewConfig(
            size: .smallest,
            colorScheme: .light,
            sizeCategory: .large,
            displayName: "Smallest iPhone"),
        PreviewConfig(
            size: .largest,
            colorScheme: .light,
            sizeCategory: .large,
            displayName: "Largest iPhone")
    ]
}

and a helper method to apply them:

extension View {

    func applyPreviewConfigs(_ configs: [PreviewConfig]) -> some View {
        Group {
            ForEach(configs) { config in
                previewDevice(config.device)
                    .preferredColorScheme(config.colorScheme)
                    .environment(\.sizeCategory, config.sizeCategory)
                    .previewDisplayName(config.displayName)
            }
        }
    }
}

which allows me to simply have previews like this:

struct HomeViewDemo_Previews: PreviewProvider {
    static var previews: some View {
        HomeViewDemo()
            .applyPreviewConfigs(.core)
    }
}