UILabel with rounded corners (Swift 5, Xcode 10.2)

RoundedCornersLabel.swift

@IBDesignable
public final class RoundedCornersLabel: UILabel {
    public override init(frame: CGRect) {
        super.init(frame: frame)
        configure()
    }

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

    public override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        configure()
    }

    public override var text: String? {
        didSet {
            if let text = text {
                calculateFrameRect(with: text)
            }
        }
    }

    private func configure() {
        font = .systemFont(ofSize: 10)
        textColor = .lightGray
        textAlignment = .center
        numberOfLines = 1

        layer.cornerRadius = 10
        layer.borderWidth = 0.7
        layer.borderColor = UIColor.lightGray.cgColor

        calculateFrameRect(with: text)
    }

    private func calculateFrameRect(with text: String?) {
        guard let text = text else { return }

        let width: CGFloat = {
            let dummyLabel = UILabel()
            dummyLabel.text = text
            dummyLabel.font = font
            dummyLabel.sizeToFit()
            return dummyLabel.frame.width + 20
        }()

        frame = CGRect(x: frame.minX,
                       y: frame.minY,
                       width: width,
                       height: frame.height)

        // Remove an old constraint when text was set
        calculatedWidthAnchor?.isActive = false
        calculatedWidthAnchor = widthAnchor.constraint(equalToConstant: width)
        calculatedWidthAnchor?.isActive = true
    }

    var calculatedWidthAnchor: NSLayoutConstraint?
}

extension RoundedCornersLabel {
    @IBInspectable var cornerRadius: CGFloat {
        get {
            return layer.cornerRadius
        }
        set {
            layer.cornerRadius = newValue
            layer.masksToBounds = newValue > 0
        }
    }

    @IBInspectable
    var borderWidth: CGFloat {
        get {
            return self.layer.borderWidth
        }
        set {
            self.layer.borderWidth = newValue
        }
    }

    @IBInspectable
    var borderColor: UIColor? {
        get {
            return UIColor(cgColor: self.layer.borderColor!)
        }
        set {
            self.layer.borderColor = newValue?.cgColor
        }
    }
}