Blog スタッフブログ

import UIKit

@MainActor
@IBDesignable
final class CheckboxControl: UIControl {

    @IBInspectable var isOn: Bool = false {
        didSet {
            guard oldValue != isOn else { return }
            updateAppearance(animated: true)
            sendActions(for: .valueChanged)
            UIAccessibility.post(notification: .announcement,
                                 argument: isOn ? "Checked" : "Unchecked")
        }
    }

    @IBInspectable var iconSize: CGFloat = 22 { didSet { invalidateIntrinsicContentSize(); setNeedsLayout() } }
    @IBInspectable var spacing: CGFloat = 8 { didSet { invalidateIntrinsicContentSize(); setNeedsLayout() } }

    @IBInspectable var onTintColor: UIColor = .systemBlue { didSet { updateAppearance(animated: false) } }
    @IBInspectable var offTintColor: UIColor = .secondaryLabel { didSet { updateAppearance(animated: false) } }

    @IBInspectable var text: String = "" { didSet { label.text = text; invalidateIntrinsicContentSize() } }
    @IBInspectable var textColor: UIColor = .label { didSet { label.textColor = textColor } }

    @IBInspectable var onSymbolName: String = "checkmark.square.fill" { didSet { updateAppearance(animated: false) } }
    @IBInspectable var offSymbolName: String = "square" { didSet { updateAppearance(animated: false) } }

    // MARK: - Views
    private let imageView = UIImageView()
    private let label = UILabel()

    // MARK: - Init
    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        commonInit()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        Task { @MainActor in
            commonInit()
            updateAppearance(animated: false)
        }
    }

    private func commonInit() {
        isAccessibilityElement = true
        accessibilityTraits = [.button]

        imageView.contentMode = .scaleAspectFit
        imageView.setContentHuggingPriority(.required, for: .horizontal)
        imageView.setContentCompressionResistancePriority(.required, for: .horizontal)

        label.textColor = textColor
        label.numberOfLines = 1

        addSubview(imageView)
        addSubview(label)

        addTarget(self, action: #selector(didTap), for: .touchUpInside)

        updateAppearance(animated: false)
    }

    // MARK: - Layout
    override func layoutSubviews() {
        super.layoutSubviews()

        let h = bounds.height
        let icon = min(iconSize, h)
        let iconY = (h - icon) / 2

        imageView.frame = CGRect(x: 0, y: iconY, width: icon, height: icon)

        let labelX = imageView.frame.maxX + (text.isEmpty ? 0 : spacing)
        let labelW = max(0, bounds.width - labelX)
        label.frame = CGRect(x: labelX, y: 0, width: labelW, height: h)
    }

    override var intrinsicContentSize: CGSize {
        let labelSize = label.intrinsicContentSize
        let w = iconSize + (text.isEmpty ? 0 : spacing + labelSize.width)
        let h = max(iconSize, labelSize.height)
        return CGSize(width: w, height: h)
    }

    // MARK: - Interaction
    @objc private func didTap() {
        isOn.toggle()
    }
    
    override var isHighlighted: Bool {
        didSet {
            let alpha: CGFloat = isHighlighted ? 0.6 : 1.0
            UIView.animate(withDuration: 0.12) { [weak self] in
                self?.alpha = alpha
            }
        }
    }

    // MARK: - Update
    private func updateAppearance(animated: Bool) {
        accessibilityLabel = text.isEmpty ? "Checkbox" : text
        accessibilityValue = isOn ? "On" : "Off"

        let symbolName = isOn ? onSymbolName : offSymbolName
        let tint = isOn ? onTintColor : offTintColor

        let config = UIImage.SymbolConfiguration(pointSize: iconSize, weight: .regular)
        let img = UIImage(systemName: symbolName, withConfiguration: config)

        let apply = { [weak self] in
            guard let self else { return }
            imageView.image = img
            imageView.tintColor = tint
            label.text = text
        }

        if animated {
            UIView.transition(with: imageView, duration: 0.15, options: .transitionCrossDissolve) {
                apply()
            }
        } else {
            apply()
        }
    }
}