UIColor + extension

UIColor + extension.md

UIColor + extension

参考URL : 【Swift】あるUIColorからあるUIColorへ変化の途中経過のUIColorを作成する

extension UIColor {
    class func colorForOffsetPercentage(percentage: CGFloat, beforeColor: UIColor, afterColor: UIColor) -> UIColor {
        let beforeRGB   = beforeColor.RGBForColor()
        let afterRGB    = afterColor.RGBForColor()
        
        let actualRed   = (afterRGB.red - beforeRGB.red) * percentage + beforeRGB.red
        let actualBlue  = (afterRGB.blue - beforeRGB.blue) * percentage + beforeRGB.blue
        let actualGreen = (afterRGB.green - beforeRGB.green) * percentage + beforeRGB.green
        let actualAlpha = (afterRGB.alpha - beforeRGB.alpha) * percentage + beforeRGB.alpha
        
        return UIColor(red: actualRed, green: actualGreen, blue: actualBlue, alpha: actualAlpha)
    }
    
    func RGBForColor() -> (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {
        var red  : CGFloat = 0.0
        var green: CGFloat = 0.0
        var blue : CGFloat = 0.0
        var alpha: CGFloat = 0.0
        getRed(&red, green: &green, blue: &blue, alpha: &alpha)
        return (red, green, blue, alpha)
    }
}

★ 16進数でUIColorを作成する

extension UIColor {
    class func hex (hexStr : NSString, alpha : CGFloat) -> UIColor {
        let hexString = hexStr.stringByReplacingOccurrencesOfString("#", withString: "")
        
        let scanner = NSScanner(string: hexString)
        var color: UInt32 = 0
        if scanner.scanHexInt(&color) {
            let r = CGFloat((color & 0xFF0000) >> 16) / 255.0
            let g = CGFloat((color & 0x00FF00) >> 8) / 255.0
            let b = CGFloat(color & 0x0000FF) / 255.0
            return UIColor(red:r,green:g,blue:b,alpha:alpha)
        } else {
            print("invalid hex string")
            return UIColor.whiteColor();
        }
    }
}

let color = UIColor.hex("#FF4500", alpha: 1.0)
color //=> r 1.0 g 0.271 b 0.0 a 1.0

★ UIColorのクラスメソッドでアクセスできる拡張

public func colorFromDecimalRGB(_ red: CGFloat, _ green: CGFloat, _ blue: CGFloat, alpha: CGFloat = 1.0) -> UIColor {
  return UIColor(
    red: red / 255.0,
    green: green / 255.0,
    blue: blue / 255.0,
    alpha: alpha
  )
}

extension UIColor {

  // MARK: Custom Defined Colors

  /// Dark Blue Aztec
  class var aztec: UIColor {
    return colorFromDecimalRGB(38, 39, 41)
  }

  /// Light Cream Color
  class var lightCream: UIColor {
    return colorFromDecimalRGB(232, 234, 221)
  }

  /// Cream Color
  class var cream: UIColor {
    return colorFromDecimalRGB(229, 231, 218)
  }

  /// Swirl Color
  class var swirl: UIColor {
    return colorFromDecimalRGB(228, 221, 202)
  }

  /// Travertine Color
  class var travertine: UIColor {
    return colorFromDecimalRGB(214, 206, 195)
  }

  /// Green
  class var ufoGreen: UIColor {
    return colorFromDecimalRGB(64, 186, 145)
  }

  class var textGrey: UIColor {
    return colorFromDecimalRGB(146, 146, 146)
  }
}