UILabelWithLineHeight.swift

@IBDesignable
public class UILabelWithLineHeight: UILabel {
    
    override public var intrinsicContentSize: CGSize {
        var size = intrinsicContentSizeWithoutPadding
        let numberOfLines = Int(ceil(size.height / font.lineHeight))
        let padding = (lineHeightMultiple - 1.0) * font.lineHeight
        size.height += CGFloat(numberOfLines - 1) * padding
        return size
    }

    override public var text: String? {
        didSet {
            updateAttributedText()
        }
    }

    @IBInspectable public var lineHeightMultiple: CGFloat = 1.0 {
        didSet {
            updateAttributedText()
        }
    }
    
    private var intrinsicContentSizeWithoutPadding: CGSize {
        let maxSize = CGSize(width: frame.size.width, height: CGFloat(MAXFLOAT))
        let text = (self.text ?? "") as NSString
        return text.boundingRect(with: maxSize, options: .usesLineFragmentOrigin, attributes: [.font: font], context: nil).size
    }
    
    private func updateAttributedText() {
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.lineHeightMultiple = lineHeightMultiple
        attributedText = NSAttributedString(string: text ?? "", attributes: [
            .font: font,
            .paragraphStyle: paragraphStyle,
            .foregroundColor: textColor
        ])
        invalidateIntrinsicContentSize()
    }
}