UIStackViewをViewBuilderで初期化できるVStackViewとHStackViewを作る

let stackView = VStackView {
  UserProfileView(imageURL)
  UserNameView(name)
}

UIStackViewを便利に使うために、ViewBuilderを作って初期化できるようにしてみます。

import UIKit

@resultBuilder
public struct ArrangedSubviewBuilder {
    public static func buildBlock(_ components: UIView...) -> [UIView] {
        components
    }
}

public class HStackView: UIStackView {
    public convenience init(
        spacing: CGFloat = UIStackView.spacingUseSystem,
        @ArrangedSubviewBuilder arrangedSubviews: () -> [UIView]
    ) {
        self.init(frame: .null)
        self.spacing = spacing
        
        self.axis = .horizontal
        for view in arrangedSubviews() {
            addArrangedSubview(view)
        }
    }
}

public class VStackView: UIStackView {
    public convenience init(
        spacing: CGFloat = UIStackView.spacingUseSystem,
        @ArrangedSubviewBuilder arrangedSubviews: () -> [UIView]
    ) {
        self.init(frame: .null)
        self.spacing = spacing
        
        self.axis = .vertical
        for view in arrangedSubviews() {
            addArrangedSubview(view)
        }
    }
}