UILabel+Extension.swift

import UIKit

extension UILabel {
    
    @IBInspectable var kerning: Float {
        get {
            var range = NSMakeRange(0, (text ?? "").characters.count)
            guard let kern = attributedText?.attribute(NSKernAttributeName, at: 0, effectiveRange: &range), let value = kern as? NSNumber else {
                return 0
            }
            return value.floatValue
        }
        set {
            var attrs: NSMutableAttributedString
            
            if let attributedText = attributedText {
                attrs = NSMutableAttributedString(attributedString: attributedText)
            } else if let text = text {
                attrs = NSMutableAttributedString(string: text)
            } else {
                attrs = NSMutableAttributedString(string: "")
            }
            
            let range = NSMakeRange(0, attrs.length)
            attrs.addAttribute(NSKernAttributeName, value: NSNumber(value: newValue), range: range)
            self.attributedText = attrs
        }
    }
    
    @IBInspectable var lineHeight: Float {
        get {
            return self.lineHeight
        }
        set {
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.lineSpacing = 1.0
            paragraphStyle.lineHeightMultiple = CGFloat(newValue)
            paragraphStyle.alignment = self.textAlignment
            
            let attrString = NSMutableAttributedString(string: self.text!)
            attrString.addAttribute(NSFontAttributeName, value: self.font, range: NSMakeRange(0, attrString.length))
            attrString.addAttribute(NSParagraphStyleAttributeName, value:paragraphStyle, range:NSMakeRange(0, attrString.length))
            self.attributedText = attrString
        }
    }
    
}