最新swift3版本

        extension UIColor {
convenience init(hexString: String) {
    let hex = hexString.trimmingCharacters(in: CharacterSet.alphanumerics.inverted)
    var int = UInt32()
    Scanner(string: hex).scanHexInt32(&int)
    let a, r, g, b: UInt32
    switch hex.characters.count {
    case 3: // RGB (12-bit)
        (a, r, g, b) = (255, (int >> 8) * 17, (int >> 4 & 0xF) * 17, (int & 0xF) * 17)
    case 6: // RGB (24-bit)
        (a, r, g, b) = (255, int >> 16, int >> 8 & 0xFF, int & 0xFF)
    case 8: // ARGB (32-bit)
        (a, r, g, b) = (int >> 24, int >> 16 & 0xFF, int >> 8 & 0xFF, int & 0xFF)
    default:
        (a, r, g, b) = (255, 0, 0, 0)
    }
      self.init(red: CGFloat(r) / 255, green: CGFloat(g) / 255, blue:      CGFloat(b) / 255, alpha: CGFloat(a) / 255)
}
}

在你的类或任何你把hexcolor转换为uicolor的地方使用这种方法

             let color1 = UIColor(hexString: "#FF323232")

在Swift 2.0和Xcode 7.0.1中，你可以创建这个函数:

    // Creates a UIColor from a Hex string.
    func colorWithHexString (hex:String) -> UIColor {
        var cString:String = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString

        if (cString.hasPrefix("#")) {
            cString = (cString as NSString).substringFromIndex(1)
        }

        if (cString.characters.count != 6) {
            return UIColor.grayColor()
        }

        let rString = (cString as NSString).substringToIndex(2)
        let gString = ((cString as NSString).substringFromIndex(2) as NSString).substringToIndex(2)
        let bString = ((cString as NSString).substringFromIndex(4) as NSString).substringToIndex(2)

        var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
        NSScanner(string: rString).scanHexInt(&r)
        NSScanner(string: gString).scanHexInt(&g)
        NSScanner(string: bString).scanHexInt(&b)


        return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
    }

然后这样使用它:

let color1 = colorWithHexString("#1F437C")

Swift 4更新

func colorWithHexString (hex:String) -> UIColor {

    var cString = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()

    if (cString.hasPrefix("#")) {
        cString = (cString as NSString).substring(from: 1)
    }

    if (cString.characters.count != 6) {
        return UIColor.gray
    }

    let rString = (cString as NSString).substring(to: 2)
    let gString = ((cString as NSString).substring(from: 2) as NSString).substring(to: 2)
    let bString = ((cString as NSString).substring(from: 4) as NSString).substring(to: 2)

    var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;
    Scanner(string: rString).scanHexInt32(&r)
    Scanner(string: gString).scanHexInt32(&g)
    Scanner(string: bString).scanHexInt32(&b)


    return UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))
}

只是对第一个答案的一些补充

(还没有检查alpha，可能需要添加一个if next > 0xffffff):

extension UIColor {

struct COLORS_HEX {
    static let Primary = 0xffffff
    static let PrimaryDark = 0x000000
    static let Accent = 0xe89549
    static let AccentDark = 0xe27b2a
    static let TextWhiteSemiTransparent = 0x80ffffff
}

convenience init(red: Int, green: Int, blue: Int, alphaH: Int) {
    assert(red >= 0 && red <= 255, "Invalid red component")
    assert(green >= 0 && green <= 255, "Invalid green component")
    assert(blue >= 0 && blue <= 255, "Invalid blue component")
    assert(alphaH >= 0 && alphaH <= 255, "Invalid alpha component")

    self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: CGFloat(alphaH) / 255.0)
}

convenience init(netHex:Int) {
    self.init(red:(netHex >> 16) & 0xff, green:(netHex >> 8) & 0xff, blue:netHex & 0xff, alphaH: (netHex >> 24) & 0xff)
}

}

另一种方法

斯威夫特3.0

为UIColor写一个扩展

// To change the HexaDecimal value to Corresponding Color
extension UIColor
{
    class func uicolorFromHex(_ rgbValue:UInt32, alpha : CGFloat)->UIColor

    {
        let red = CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0
        let green = CGFloat((rgbValue & 0xFF00) >> 8) / 255.0
        let blue = CGFloat(rgbValue & 0xFF) / 255.0
        return UIColor(red:red, green:green, blue:blue, alpha: alpha)
    }
}

你可以像这样用hex直接创建UIColor

let carrot = UIColor.uicolorFromHex(0xe67e22, alpha: 1))

我从这个回答中总结了一些想法，并针对iOS 13和Swift 5进行了更新。

extension UIColor {
  
  convenience init(_ hex: String, alpha: CGFloat = 1.0) {
    var cString = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()
    
    if cString.hasPrefix("#") { cString.removeFirst() }
    
    if cString.count != 6 {
      self.init("ff0000") // return red color for wrong hex input
      return
    }
    
    var rgbValue: UInt64 = 0
    Scanner(string: cString).scanHexInt64(&rgbValue)
    
    self.init(red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
              green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
              blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
              alpha: alpha)
  }

}

然后你可以这样使用它:

UIColor("#ff0000") // with #
UIColor("ff0000")  // without #
UIColor("ff0000", alpha: 0.5) // using optional alpha value

斯威夫特5.0

你不能在Swift中直接使用#ffffff语法。以下是我用于网络相关项目的代码。支持alpha和三位数字。

用法示例(大写值也可以):

    let hex = "#FADE2B"  // yellow
    let color = NSColor(fromHex: hex)

支持的字符串格式:

"fff" // RGB "#fff" // #RGB "ffff" // RGBA "#ffff" // #RGBA . "ffffff" // RRGGBB . "#ffffff" // #RRGGBB . "ffffffff" // RRGGBBAA . "#ffffffff" // #RRGGBBAA .

数字代表红色，绿色，蓝色和阿尔法(像透明度)。对于iOS，用UIColor替换NSColor。

代码:

    extension NSColor {
        /// Initialises NSColor from a hexadecimal string. Color is clear if string is invalid.
        /// - Parameter fromHex: supported formats are "#RGB", "#RGBA", "#RRGGBB", "#RRGGBBAA", with or without the # character
        public convenience init(fromHex:String) {
            var r = 0, g = 0, b = 0, a = 255
            let offset = fromHex.hasPrefix("#") ? 1 : 0
            let ch = fromHex.map{$0}
            switch(ch.count - offset) {
            case 8:
                a = 16 * (ch[offset+6].hexDigitValue ?? 0) + (ch[offset+7].hexDigitValue ?? 0)
                fallthrough
            case 6:
                r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
                g = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
                b = 16 * (ch[offset+4].hexDigitValue ?? 0) + (ch[offset+5].hexDigitValue ?? 0)
                break
            case 4:
                a = 16 * (ch[offset+3].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
                fallthrough
            case 3:  // Three digit #0D3 is the same as six digit #00DD33
                r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+0].hexDigitValue ?? 0)
                g = 16 * (ch[offset+1].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
                b = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+2].hexDigitValue ?? 0)
                break
            default:
                a = 0
                break
            }
            self.init(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: CGFloat(a)/255)
            
        }
    }
    // Author: Andrew Kingdom

授权:CC BY

我发现这比下面的复制/粘贴更整洁

选择:

您可以删除#并将其存储为32位无符号整数字面量，由0x前缀表示，即0xffffff。不过，你仍然需要代码将其转换为颜色。

如果你想要一种非编程的方式来获取颜色:打开一个颜色选择器对话框，切换到colour Sliders > RGB Sliders，并将值粘贴/输入到“Hex color #”框中。(不要粘贴#散列符号。)