Swift - UIColor.black 在从 UIColor 转换为字符串时使应用程序崩溃

Question

例如，下面的代码与 UIColor.Purple 或 UIColor.Yellow 一起工作正常，但当我使用 UIColor.black 时应用程序崩溃。

fatal error :索引超出范围使用 UIColor.black 时，组件 [2] 和 [3] 似乎不存在。我知道我正在强制展开，但不应该所有颜色都有 RGBA 吗？

//UIColor RGBA to string
public extension UIColor {

class func StringFromUIColor(color: UIColor) -> String{
    let components = color.cgColor.components
    return "[\(components![0]), \(components![1]), \(components![2]), \(components![3])]"
}

class func UIColorFromString(string: String) -> UIColor {
    let componentsStringStepOne = string.replacingOccurrences(of: "[", with: "")
    let componentsString = componentsStringStepOne.replacingOccurrences(of: "]", with: "")
    let components = componentsString.components(separatedBy: ", ")
    return UIColor(red: CGFloat((components[0] as NSString).floatValue), green: CGFloat((components[1] as NSString).floatValue), blue: CGFloat((components[2] as NSString).floatValue), alpha: CGFloat((components[3] as NSString).floatValue))
}

还有没有更好的方法来编写这部分代码？

let componentsStringStepOne = string.replacingOccurrences(of: "[", with: "")
    let componentsString = componentsStringStepOne.replacingOccurrences(of: "]", with: "")
    let components = componentsString.components(separatedBy: ", ")

感谢任何帮助!谢谢。

Answer 1

这是我在 rmaddy 和 kamran 回复后想出的解决方案。它没有使应用程序崩溃，而且我得到了正确的颜色。它在 plist 中保存了我希望它看起来是黑色还是彩色，例如。 [0.2,0.4,0.5,1.0]。感谢您的帮助

public extension UIColor {

class func StringFromUIColor(color: UIColor) -> String{
    let components = color.cgColor.components
    if components?.count == 2 {
         return "[\(components![0]), \(components![0]), \(components![0]), \(components![1])]"
    } else {
        return "[\(components![0]), \(components![1]), \(components![2]), \(components![3])]"
    }
}

class func UIColorFromString(string: String) -> UIColor {
    let componentsStringStepOne = string.replacingOccurrences(of: "[", with: "")
    let componentsString = componentsStringStepOne.replacingOccurrences(of: "]", with: "")
    let components = componentsString.components(separatedBy: ", ")
    if components.count == 2 {
        return UIColor(white: CGFloat((components[0] as NSString).floatValue), alpha: CGFloat((components[1] as NSString).floatValue))
    } else {
          return UIColor(red: CGFloat((components[0] as NSString).floatValue), green: CGFloat((components[1] as NSString).floatValue), blue: CGFloat((components[2] as NSString).floatValue), alpha: CGFloat((components[3] as NSString).floatValue))
    }
  }
}