你可以做这样的扩展

extension UIColor {
    convenience init(hex: UInt, alpha: CGFloat = 1) {
        self.init(
            red: CGFloat((hex & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((hex & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(hex & 0x0000FF) / 255.0,
            alpha: alpha
        )
    }
}

像这样用在任何地方

let color1 = UIColor(hex: 0xffffff)
let color2 = UIColor(hex: 0xffffff, alpha: 0.2)

你可以做这样的扩展

extension UIColor {
    convenience init(hex: UInt, alpha: CGFloat = 1) {
        self.init(
            red: CGFloat((hex & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((hex & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(hex & 0x0000FF) / 255.0,
            alpha: alpha
        )
    }
}

像这样用在任何地方

let color1 = UIColor(hex: 0xffffff)
let color2 = UIColor(hex: 0xffffff, alpha: 0.2)

有一个很好的UIColor类别，其中有许多功能。

用法:

textView.textColor = [UIColor colorWithHexString:textColorHex];
NSLog(@"Text Color Hex: %@", textColorHex);

其中textColorHex有一个形式的@“FFFFFF”没有#符号。

大多数发布的解决方案使用了Scanner，但至少在现代Swift中你并不真正需要它。相反，你可以简单地使用UInt init和基数16，然后使用基本的二进制操作来获得UIColor组件:

func stringToColor(color: String) -> UIColor {
    guard let i = UInt(color, radix: 16) else {
        return UIColor.white
    }
    return UIColor(
        red: CGFloat((i & 0xFF0000) >> 16) / 255.0,
        green: CGFloat((i & 0xFF00) >> 8) / 255.0,
        blue: CGFloat(i & 0xFF) / 255.0,
        alpha: 1.0
    )
}

这个解决方案期望输入像“FF00FF”，你可能需要删除前面的哈希符号(#)，如果你的字符串中有一个。

extension UIColor 
{
    class func fromHexaString(hex:String) -> UIColor
    {
        let scanner           = Scanner(string: hex)
        scanner.scanLocation  = 0
        var rgbValue: UInt64  = 0
        scanner.scanHexInt64(&rgbValue)

        return UIColor(
            red: CGFloat((rgbValue & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgbValue & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgbValue & 0x0000FF) / 255.0,
            alpha: CGFloat(1.0)
        )
    }
}

//you can call like this.

UIColor.fromHexaString(hex:3276b1)

Swift 2.0版本的解决方案，将处理alpha值的颜色和完美的错误处理:

func RGBColor(hexColorStr : String) -> UIColor?{

    var red:CGFloat = 0.0
    var green:CGFloat = 0.0
    var blue:CGFloat = 0.0
    var alpha:CGFloat = 1.0

    if hexColorStr.hasPrefix("#"){

        let index   = hexColorStr.startIndex.advancedBy(1)
        let hex     = hexColorStr.substringFromIndex(index)
        let scanner = NSScanner(string: hex)
        var hexValue: CUnsignedLongLong = 0

        if scanner.scanHexLongLong(&hexValue)
        {
            if hex.characters.count == 6
            {
                red   = CGFloat((hexValue & 0xFF0000) >> 16) / 255.0
                green = CGFloat((hexValue & 0x00FF00) >> 8)  / 255.0
                blue  = CGFloat(hexValue & 0x0000FF) / 255.0
            }
            else if hex.characters.count == 8
            {
                red   = CGFloat((hexValue & 0xFF000000) >> 24) / 255.0
                green = CGFloat((hexValue & 0x00FF0000) >> 16) / 255.0
                blue  = CGFloat((hexValue & 0x0000FF00) >> 8)  / 255.0
                alpha = CGFloat(hexValue & 0x000000FF)         / 255.0
            }
            else
            {
                print("invalid hex code string, length should be 7 or 9", terminator: "")
                return nil
            }
        }
        else
        {
            print("scan hex error")
       return nil
        }
    }

    let color: UIColor =  UIColor(red:CGFloat(red), green: CGFloat(green), blue:CGFloat(blue), alpha: alpha)
    return color
}