Adding SwiftUI preview implementation to existing view class

TableViewCell.swift

//
//  TableViewCell.swift
//  iOS12App
//
//  Created by Kazuma Koze on 2020/03/05.
//  Copyright © 2020 Climb App. All rights reserved.
//

import UIKit
import SwiftUI

class TableViewCell: UITableViewCell {

    @IBOutlet weak var titleLabel: UILabel!
    @IBOutlet weak var subheadLabel: UILabel!
    @IBOutlet weak var bodyLabel: UILabel!

    @IBOutlet weak var stackView: UIStackView!
    
    override func awakeFromNib() {
        super.awakeFromNib()
        // for SwiftUI preview
        setContentHuggingPriority(.defaultHigh, for: .vertical)
        
        updateStackViewAxis(traitCollection.preferredContentSizeCategory.isAccessibilityCategory)
    }

    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        let isAccessibilityCategory = traitCollection.preferredContentSizeCategory.isAccessibilityCategory
        if isAccessibilityCategory != previousTraitCollection?.preferredContentSizeCategory.isAccessibilityCategory {
            updateStackViewAxis(isAccessibilityCategory)
        }
    }
    
    private func updateStackViewAxis(_ isAccessibilityCategory: Bool) {
        stackView.axis = isAccessibilityCategory ? .vertical : .horizontal
        stackView.alignment = isAccessibilityCategory ? .leading : .center
    }

    // for SwiftUI preview
    override var intrinsicContentSize: CGSize {
        return systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
    }
}

#if DEBUG
@available(iOS 13.0, *)
struct TableViewCellPreview: PreviewProvider, UIViewRepresentable {
    
    typealias UIViewType = TableViewCell
    
    static var previews: some View {
        Group {
            Self()
                .environment(\.sizeCategory, .medium)
                .previewLayout(.sizeThatFits)
            Self()
                .environment(\.sizeCategory, .accessibilityExtraExtraExtraLarge)
                .previewLayout(.sizeThatFits)
        }
    }
    
    func makeUIView(context: UIViewRepresentableContext<Self>) -> UIViewType {
        let nib = UINib(nibName: String(describing: UIViewType.self), bundle: nil)
        let cell = nib.instantiate(withOwner: nil, options: nil).first as! UIViewType
        return cell
    }
    
    func updateUIView(_ uiView: UIViewType, context: UIViewRepresentableContext<Self>) {
    }
}
#endif