UIKitView builder + constraints

UIKitBuilder.swift

//
//  ViewController.swift
//  pocUIViewBuilder
//
//  Created by MaxAir on 26/05/2023.
//

import UIKit
@resultBuilder
struct SubviewBuilder {
    static func buildEither(first component: UIView) -> UIView {
        print(#function + "2")
        return component
    }
    
    static func buildEither(second component: UIView) -> UIView {
        print(#function + "1")
        return component
    }
    static func buildBlock(_ components: UIView...) -> UIView {
        print(#function  + "2" + components.map { $0.tag }.description)
        let view = IfBlockView()
        components.forEach { view.addSubview($0) }
        return view
    }
    static func buildBlock(_ components: UIView...) -> [UIView] {
        print(#function + "1" + components.map { $0.tag }.description)
        let result = components.flatMap {
            if $0 is IfBlockView {
                return $0.subviews
            } else {
                return [$0]
            }
        }
        return result
    }
    static func buildOptional(_ component: UIView?) -> UIView {
        print(#function + "2" + (component?.description ?? "-") ?? "-")
        return component ?? UIView()
    }
    static func buildIf(_ component: UIView?) -> [UIView] {
        print(#function)
        switch component {
        case .none:
            return []
        case .some(let wrapped):
            return [wrapped]
        }
    }
}

class IfBlockView: UIView { }

extension UIView {
    @discardableResult
    func addSubviews(@SubviewBuilder builder: () -> [UIView]) -> UIView {
        builder().forEach { addSubview($0) }
        return self
    }
    
    convenience init(tag: Int) {
        self.init(frame: .zero)
        self.tag = tag
    }
    
    @discardableResult
    func configureConstraints(_ builder: (_ outlet: UIView) -> [NSLayoutConstraint]) -> Self {
        let constraints = builder(self)
        constraints.forEach { $0.isActive = true }
        self.addConstraints(constraints)
        return self
    }
}

extension UIStackView {
    convenience init(axis: NSLayoutConstraint.Axis) {
        self.init()
        self.axis = .horizontal
        self.axis = axis
    }
}

extension UIView {
    func outlet<T: UIView>(_ outlet: inout T?) -> Self {
        outlet = self as? T
        return self
    }
}

class ViewController: UIViewController {
    
    var stackView: UIStackView!
    var labelTitle: UILabel!
    var labelOne: UILabel!
    var labelTwo: UILabel!
    var labelThree: UILabel!
    var labelFour: UILabel!
    var labelFive: UILabel!
    var buttonMain: UIButton!
    var cell: UITableViewCell!

    override func viewDidLoad() {
        super.viewDidLoad()
        createView()
        configureAutoLayout()
    }
    
    private func createView() {
        view.addSubviews {
            UIStackView(axis: .horizontal).outlet(&stackView).addSubviews {
                if true {
                    UILabel().outlet(&labelTitle).configureConstraints { outlet in
                    [
                        outlet.widthAnchor.constraint(equalToConstant: 20),
                        outlet.heightAnchor.constraint(equalToConstant: 10),
                    ]
                    }
                }
                UILabel().outlet(&labelOne)
                UIButton(primaryAction: .init(handler: { _ in
                    print("")
                })).outlet(&buttonMain)
                UIButton(type: .contactAdd).outlet(&buttonMain)
                UILabel().outlet(&labelTwo)
                if true {
                    UILabel().outlet(&labelThree)
                }
            }.configureConstraints { outlet in
                [
                    outlet.widthAnchor.constraint(equalToConstant: 20),
                    outlet.heightAnchor.constraint(equalToConstant: 10),
                ]
            }
        }
    }
    
    private func configureAutoLayout() {
        labelTitle.configureConstraints { outlet in
            [
                outlet.widthAnchor.constraint(equalToConstant: 20),
                outlet.heightAnchor.constraint(equalToConstant: 10),
            ]
        }
    }
}