weareopensource/Swift

/**
 * Dependencies
 */

import UIKit

/**
* Extension
*/

extension UIColor {

    /**
     * @desc lighter color
     * @param {CGFloat} percentage,
     */
    func lighter(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: abs(percentage) )
    }

    /**
     * @desc darker color
     * @param {CGFloat} percentage,
     */
    func darker(by percentage: CGFloat = 30.0) -> UIColor? {
        return self.adjust(by: -1 * abs(percentage) )
    }

    /**
     * @desc adjust color darkness / lightness from coefficient
     * @param {CGFloat} percentage,
     */
    func adjust(by percentage: CGFloat = 30.0) -> UIColor? {
        var red: CGFloat = 0, green: CGFloat = 0, blue: CGFloat = 0, alpha: CGFloat = 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
        }
    }

    func toHex(alpha: Bool = false) -> String? {
        guard let components = cgColor.components, components.count >= 3 else {
            return nil
        }

        let r = Float(components[0])
        let g = Float(components[1])
        let b = Float(components[2])
        var a = Float(1.0)

        if components.count >= 4 {
            a = Float(components[3])
        }

        if alpha {
            return String(format: "%02lX%02lX%02lX%02lX", lroundf(r * 255), lroundf(g * 255), lroundf(b * 255), lroundf(a * 255))
        } else {
            return String(format: "%02lX%02lX%02lX", lroundf(r * 255), lroundf(g * 255), lroundf(b * 255))
        }
    }

}