RepresentablePreview.swift

//
//  Created by Volodymyr Andriienko on 18.05.2021.
//  Copyright © 2021 VAndrJ. All rights reserved.
//

#if DEBUG
#if canImport(SwiftUI)
import SwiftUI

@available (iOS 13.0, *)
struct Representable: UIViewRepresentable {
    let view: UIView
    
    func makeUIView(context: Context) -> UIView {
        return view
    }
    
    func updateUIView(_ uiView: UIView, context: Context) {}
}

enum RepresentablePreviewLayout {
    case fixed(CGSize)
    case auto
    case frameInherited
    case undefined
    case flexibleWidth(height: CGFloat)
    case flexibleHeight(width: CGFloat)
}

@available (iOS 13.0, *)
extension UIView {
    
    func sRepresentation(layout: RepresentablePreviewLayout) -> AnyView {
        switch layout {
        case let .fixed(size):
            return Representable(view: self)
                .frame(width: size.width, height: size.height, alignment: .topLeading)
                .previewLayout(.sizeThatFits)
                .anyView
        case .auto:
            let size = systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
            return Representable(view: self)
                .frame(width: size.width, height: size.height)
                .previewLayout(.sizeThatFits)
                .anyView
        case .frameInherited:
            return Representable(view: self)
                .frame(width: frame.width, height: frame.height)
                .previewLayout(.sizeThatFits)
                .anyView
        case .undefined:
            return Representable(view: self)
                .anyView
        case let .flexibleWidth(height):
            frame.size = CGSize(width: UIView.layoutFittingExpandedSize.width, height: height)
            setNeedsLayout()
            layoutIfNeeded()
            let size = systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
            return Representable(view: self)
                .frame(width: size.width, height: height, alignment: .topLeading)
                .previewLayout(.sizeThatFits)
                .anyView
        case let .flexibleHeight(width):
            frame.size = CGSize(width: width, height: UIView.layoutFittingExpandedSize.height)
            setNeedsLayout()
            layoutIfNeeded()
            let size = systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
            return Representable(view: self)
                .frame(width: width, height: size.height, alignment: .topLeading)
                .previewLayout(.sizeThatFits)
                .anyView
        }
    }
}

@available (iOS 13.0, *)
extension View {
    var anyView: AnyView {
        return AnyView(self)
    }
}
#endif
#endif