UIColor extension

UIColor extension.swift

extension UIColor {
    
    func setLighter(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: abs(percentage) )
    }
    
    func setDarker(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: -1 * abs(percentage) )
    }
    
    func adjust(by percentage: CGFloat = 30.0) -> UIColor? {
        var red: CGFloat = 0.0, green: CGFloat = 0.0, blue: CGFloat = 0.0, alpha: CGFloat = 0.0
        if self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
            return UIColor(red: min(red + percentage / 100, 1.0),
                           green: min(green + percentage / 100, 1.0),
                           blue: min(blue + percentage / 100, 1.0),
                           alpha: alpha)
        } else {
            return nil
        }
    }
}