CGColorからカラーコードを生成

CGColorToHexCode.swift

extension CGColor {
    // convert to color-code string
    public var hexCodeRepresentation: String? {
        get{
            guard let components = self.components else {return nil}
            let colorCode = components.map({$0 * 255.0})
                .compactMap({UInt8($0)})
                .map({String(format: "%02X", $0)})
                .joined()
            return "#\(colorCode)"
        }
    }
}