如何将UIColor转换为黑白UIColor

extension UIColor {
    func convertToBlackAndWhite() -> UIColor? {
        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0
        
        if self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) {
            let gray = 0.299 * red + 0.587 * green + 0.114 * blue
            return UIColor(red: gray, green: gray, blue: gray, alpha: alpha)
        }
        
        return nil
    }
}

let originalColor = UIColor(red: 0.4, green: 0.6, blue: 0.8, alpha: 1.0)
if let convertedColor = originalColor.convertToBlackAndWhite() {
    // 使用转换后的颜色
    print(convertedColor)
} else {
    // 转换失败
    print("转换失败")
}