Get lighter and darker color variations for a given UIColor

Question

How to get different lighter and darker variations of a given UIColor in Swift?

Answer 1

Using lukszar clampled function, I wrote this function for the UIColor extension, using real proportions of RGB values. I hope it is helpful

public extension UIColor {

  public func lighter(by percentage: CGFloat = 30.0) -> UIColor {
    return self.adjustBrightness(by: abs(percentage))
  }

  public func darker(by percentage: CGFloat = 30.0) -> UIColor {
    return self.adjustBrightness(by: -abs(percentage))
  }

  func adjustBrightness(by percentage: CGFloat = 30.0) -> UIColor {

    let ratio = percentage/100

    var red:   CGFloat = 0.0
    var green: CGFloat = 0.0
    var blue:  CGFloat = 0.0
    var alpha: CGFloat = 0.0

    if self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
      let newRed =   (red   + ((ratio < 0) ? red   * ratio : (1 - red)   * ratio)).clamped(to: 0.0 ... 1.0)
      let newGreen = (green + ((ratio < 0) ? green * ratio : (1 - green) * ratio)).clamped(to: 0.0 ... 1.0)
      let newBlue =  (blue  + ((ratio < 0) ? blue  * ratio : (1 - blue)  * ratio)).clamped(to: 0.0 ... 1.0)
      return UIColor(red: newRed, green: newGreen, blue: newBlue, alpha: alpha)
    }
    return self
  }
}