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
}

斯威夫特2.0:

将此方法添加到VC或扩展UIColor。

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))
    }

用法:

    loginButton.tintColor = self.colorWithHexString("#be1337")

     OR

    let hexColor = self.colorWithHexString("#be1337")

这是另一种选择。

- (UIColor *)colorWithRGBHex:(UInt32)hex
{
    int r = (hex >> 16) & 0xFF;
    int g = (hex >> 8) & 0xFF;
    int b = (hex) & 0xFF;

    return [UIColor colorWithRed:r / 255.0f
                           green:g / 255.0f
                            blue:b / 255.0f
                           alpha:1.0f];
}

上面的几个解决方案涉及到一些不必要的nsstring使用。这个UIColor类扩展更简单更快:

+ colorWithHex:(UInt32)hex alpha:(CGFloat)alpha
{
    return [UIColor colorWithRed:((hex & 0xFF0000) >> 16)/255.0
                           green:((hex & 0x00FF00) >> 8)/255.0
                            blue:( hex & 0x0000FF)/255.0
                           alpha:alpha];
}

简单来说:

return [UIColor colorWithHex:0x006400 alpha:1.0]; // HTML darkgreen

据我所知，没有从十六进制字符串到UIColor(或CGColor)的内置转换。但是，您可以很容易地为此目的编写几个函数—例如，参见iphone开发访问uicolor组件

您可以使用各种在线工具将HEX字符串转换为实际的UIColor。查看uicolor.org或UI颜色选择器。输出将被转换为Objective-C代码，如下所示:

[UIColor colorWithRed:0.93 green:0.80 blue:0.80 alpha:1.0];

可以嵌入到应用程序中。希望这能有所帮助!