UILabel+Extension.swift

extension UILabel {
    
    @objc
    func set(underLineFor keyword: String) {
        guard let text = self.text ?? self.attributedText?.string else { return }

        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        let indices = attributedString.string.indicesOf(string: keyword)
        let length = keyword.count
        
        for index in indices {
            attributedString.addAttribute(NSAttributedString.Key.underlineStyle , value: NSUnderlineStyle.single.rawValue, range: NSRange(location: index, length: length))
        }
        attributedText = attributedString
    }
    
    @objc
    func set(color: UIColor, forKeyword keyword: String) {
        guard let text = self.text ?? self.attributedText?.string else { return }
        
        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        let indices = attributedString.string.indicesOf(string: keyword)
        let length = keyword.count
        
        for index in indices {
            attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: NSRange(location: index, length: length))
        }
        attributedText = attributedString
    }
    
    @objc
    func set(font: UIFont, forKeyword keyword: String) {
        guard let text = self.text ?? self.attributedText?.string else { return }
        
        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        let indices = attributedString.string.indicesOf(string: keyword)
        let length = keyword.count
        
        for index in indices {
            attributedString.addAttribute(NSAttributedString.Key.font, value: font, range: NSRange(location: index, length: length))
        }
        attributedText = attributedString
    }

    func set(font: UIFont, color: UIColor, forKeyword keyword: String) {
        guard let text = self.text ?? self.attributedText?.string else { return }
        
        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        let indices = attributedString.string.indicesOf(string: keyword)
        let length = keyword.count
        
        for index in indices {
            attributedString.addAttribute(NSAttributedString.Key.font, value: font, range: NSRange(location: index, length: length))
            attributedString.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: NSRange(location: index, length: length))
        }
        attributedText = attributedString
    }

    public func lines() -> Int {
        guard let text = self.text ?? self.attributedText?.string, let cFont = self.font else {
            return 0
        }
        let constraintRect = CGSize(width: bounds.width, height: CGFloat.greatestFiniteMagnitude)
        let boundingBox = text.boundingRect(with: constraintRect, options: .usesLineFragmentOrigin, attributes: [NSAttributedString.Key.font: cFont], context: nil)
        let count = Int(lroundf(Float(boundingBox.height)) / lroundf(Float(font.lineHeight)))
        return count
    }
    
    func set(lineHeight: CGFloat) {
        guard let text = self.text ?? self.attributedText?.string else { return }

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.minimumLineHeight = lineHeight
        paragraphStyle.alignment = self.textAlignment
        
        let attribute = [.paragraphStyle: paragraphStyle] as [NSAttributedString.Key: Any]
        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        
        attributedString.addAttributes(attribute, range: NSMakeRange(0, (self.text?.count)!))
        self.attributedText = attributedString
    }
    
    func set(letterSpacing: CGFloat) {
        guard let text = self.text ?? self.attributedText?.string else { return }
        
        let attributedString = self.attributedText.map(NSMutableAttributedString.init(attributedString:)) ?? NSMutableAttributedString(string: text)
        attributedString.addAttribute(NSAttributedString.Key.kern, value: letterSpacing, range: NSMakeRange(0, (self.text?.count)!))
        self.attributedText = attributedString
    }
}