バッジ付きのUIButton

BadgeButton.swift

import UIKit

@IBDesignable
class BadgeButton: UIButton {

    // MARK: IBInspectable

    @IBInspectable var cornerRadius: CGFloat = 8 {
        didSet {
            layer.cornerRadius = cornerRadius
        }
    }
    @IBInspectable var badgeSize: CGFloat = 28
    @IBInspectable var badgeColor: UIColor = .blue
    @IBInspectable var badgeLabelColor: UIColor = .white

    // MARK: Properties

    private let badgeView = UIView()
    private let badgeLabel = UILabel()

    override var isEnabled: Bool {
        didSet {
            alpha = isEnabled ? 1 : 0.4
        }
    }

    // MARK: Initializer

    override init(frame: CGRect) {
        super.init(frame: frame)
        commonInit()
    }

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

    override func awakeFromNib() {
        super.awakeFromNib()
        commonInit()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        commonInit()

        if let title = title(for: state) {
            setAttributedTitle(NSAttributedString(string: title, attributes: [NSAttributedString.Key(String(kCTLanguageAttributeName)): "ja"]), for: .normal)
        }
    }

    private func commonInit() {
        // - View
        isExclusiveTouch = true
        clipsToBounds = false
        // - Layer
        layer.cornerRadius = cornerRadius

        setupViews()
    }

    private func setupViews() {
        // - Badge View
        badgeView.backgroundColor = badgeColor
        badgeView.alpha = 0
        badgeView.isHidden = true
        badgeView.layer.cornerRadius = badgeSize / 2
        badgeView.isUserInteractionEnabled = false
        badgeView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(badgeView)

        NSLayoutConstraint.activate([
            badgeView.topAnchor.constraint(equalTo: topAnchor, constant: -(badgeSize / 2)),
            badgeView.trailingAnchor.constraint(equalTo: trailingAnchor, constant: badgeSize / 2),
            badgeView.widthAnchor.constraint(equalToConstant: badgeSize),
            badgeView.heightAnchor.constraint(equalToConstant: badgeSize)
        ])
        // - Badge Label
        badgeLabel.textColor = badgeLabelColor
        badgeLabel.backgroundColor = .clear
        badgeLabel.font = .systemFont(ofSize: 12, weight: .bold)
        badgeLabel.numberOfLines = 1
        badgeLabel.textAlignment = .center
        badgeLabel.translatesAutoresizingMaskIntoConstraints = false
        badgeView.addSubview(badgeLabel)

        NSLayoutConstraint.activate([
            badgeLabel.topAnchor.constraint(equalTo: badgeView.topAnchor, constant: 0),
            badgeLabel.leadingAnchor.constraint(equalTo: badgeView.leadingAnchor, constant: 0),
            badgeLabel.trailingAnchor.constraint(equalTo: badgeView.trailingAnchor, constant: 0),
            badgeLabel.bottomAnchor.constraint(equalTo: badgeView.bottomAnchor, constant: 0)
        ])
    }

    func setCount(_ badgeCount: Int) {
        badgeLabel.text = badgeCount > 99 ? "99+" : "\(badgeCount)"
        UIView.animate(withDuration: 0.3, animations: {
            self.badgeView.alpha = 0 >= badgeCount ? 0 : 1
            self.badgeView.isHidden = 0 >= badgeCount
        })
    }
}