从Hex中获取CGColor ( OS )

Question

我正在实现我的第一个OS应用程序，我创建了一个CGColor扩展。有没有办法从一个十六进制字符串中得到一个CGColor？

谢谢！

Answer 1

下面是从NSColor获取HexString的扩展

public extension NSColor {

public convenience init?(hexString: String) {
    self.init(hexString: hexString, alpha: 1.0)
}

public convenience init?(hexString: String, alpha: Float) {
    var hex = hexString

    // Check for hash and remove the hash
    if hex.hasPrefix("#") {
        hex = hex.substringFromIndex(hex.startIndex.advancedBy(1))
    }

    if (hex.rangeOfString("(^[0-9A-Fa-f]{6}$)|(^[0-9A-Fa-f]{3}$)", options: .RegularExpressionSearch) != nil) {

        // Deal with 3 character Hex strings
        if hex.characters.count == 3 {
            let redHex   = hex.substringToIndex(hex.startIndex.advancedBy(1))
            let greenHex = hex.substringWithRange(Range<String.Index>(start: hex.startIndex.advancedBy(1), end: hex.startIndex.advancedBy(2)))
            let blueHex  = hex.substringFromIndex(hex.startIndex.advancedBy(2))

            hex = redHex + redHex + greenHex + greenHex + blueHex + blueHex
        }

        let redHex = hex.substringToIndex(hex.startIndex.advancedBy(2))
        let greenHex = hex.substringWithRange(Range<String.Index>(start: hex.startIndex.advancedBy(2), end: hex.startIndex.advancedBy(4)))
        let blueHex = hex.substringWithRange(Range<String.Index>(start: hex.startIndex.advancedBy(4), end: hex.startIndex.advancedBy(6)))

        var redInt:   CUnsignedInt = 0
        var greenInt: CUnsignedInt = 0
        var blueInt:  CUnsignedInt = 0

        NSScanner(string: redHex).scanHexInt(&redInt)
        NSScanner(string: greenHex).scanHexInt(&greenInt)
        NSScanner(string: blueHex).scanHexInt(&blueInt)

        self.init(red: CGFloat(redInt) / 255.0, green: CGFloat(greenInt) / 255.0, blue: CGFloat(blueInt) / 255.0, alpha: CGFloat(alpha))
    }
    else {
        // Note:
        // The swift 1.1 compiler is currently unable to destroy partially initialized classes in all cases,
        // so it disallows formation of a situation where it would have to.  We consider this a bug to be fixed
        // in future releases, not a feature. -- Apple Forum
        self.init()
        return nil
    }
}

示例：

let color: NSColor = NSColor(hexString: "#ff8942").CGColor

Answer 2

编辑:为Mac更新

我推荐一些我经常使用的东西。下面是我的NSColorExtension，它是NSColor类的一个扩展：

 /**
 * A NSColor extension
 **/
public extension NSColor {

  /**
   Returns an NSColor instance from the given hex value

   - parameter rgbValue: The hex value to be used for the color
   - parameter alpha:    The alpha value of the color

   - returns: A NSColor instance from the given hex value
   */
  public class func hexColor(rgbValue: Int, alpha: CGFloat = 1.0) -> NSColor {

    return NSColor(red: ((CGFloat)((rgbValue & 0xFF0000) >> 16))/255.0, green:((CGFloat)((rgbValue & 0xFF00) >> 8))/255.0, blue:((CGFloat)(rgbValue & 0xFF))/255.0, alpha:alpha)

  }

}

您可以这样使用它：

NSColor.hexColor(0xff0000, alpha: 0.8)

alpha值的默认值为1.0，因此如果您不想显式显示alpha值：

NSColor.hexColor(0xff0000)

如果您想要CGColor值，可以使用以下方法：

NSColor.hexColor(0xff0000).CGColor