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")

我最终为UIColor创建了一个类别，我可以在我的其他项目中重用，并添加了这个函数:

+ (UIColor *)colorFromHex:(unsigned long)hex
{
    return [UIColor colorWithRed:((float)((hex & 0xFF0000) >> 16))/255.0
                           green:((float)((hex & 0xFF00) >> 8))/255.0
                            blue:((float)(hex & 0xFF))/255.0
                           alpha:1.0];
}

用法是这样的:

UIColor *customRedColor = [UIColor colorFromHex:0x990000];

这比传递字符串并将其转换为数字然后移位位要快得多。

你也可以从你的.pch文件中导入类别，这样你就可以很容易地在你的应用程序中到处使用colorFromHex，就像它内置到UIColor中一样:

#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    // Your other stuff here...
    #import "UIColor+HexColor.h"
#endif

你可以创建UIColor的扩展类:-

扩展UIColor {

// MARK: - getColorFromHex ／** 此函数将颜色十六进制代码转换为RGB。

- parameter color  hex string.

- returns: RGB color code.
*/
class func getColorFromHex(hexString:String)->UIColor{

    var rgbValue : UInt32 = 0
    let scanner:NSScanner =  NSScanner(string: hexString)

    scanner.scanLocation = 1
    scanner.scanHexInt(&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))
}

}

extension UIColor {
    convenience init(hexaString: String, alpha: CGFloat = 1) {
        let chars = Array(hexaString.dropFirst())
        self.init(red:   .init(strtoul(String(chars[0...1]),nil,16))/255,
                  green: .init(strtoul(String(chars[2...3]),nil,16))/255,
                  blue:  .init(strtoul(String(chars[4...5]),nil,16))/255,
                  alpha: alpha)}
}

用法:

let redColor       = UIColor(hexaString: "#FF0000")              // r 1,0 g 0,0 b 0,0 a 1,0
let transparentRed = UIColor(hexaString: "#FF0000", alpha: 0.5)  // r 1,0 g 0,0 b 0,0 a 0,5

另一种选择是将六值转换为无符号整数，并从中提取相应的值:

extension UIColor {
    convenience init(hexaString: String, alpha: CGFloat = 1) {
        self.init(hexa: UInt(hexaString.dropFirst(), radix: 16) ?? 0, alpha: alpha)
    }
    convenience init(hexa: UInt, alpha: CGFloat = 1) {
        self.init(red:   .init((hexa & 0xff0000) >> 16) / 255,
                  green: .init((hexa & 0xff00  ) >>  8) / 255,
                  blue:  .init( hexa & 0xff    )        / 255,
                  alpha: alpha)
    }
}

let purpleColor       = UIColor(hexaString: "#FF00FF")    // r 1,0 g 0,0 b 1,0 a 1,0
let transparentYellow = UIColor(hexaString: "#FFFF00", alpha: 0.5)  // r 1,0 g 1,0 b 0,0 a 0,5

伊森·斯特里德回答的简单例子。一个接受十六进制字符串并返回UIColor的函数。 (你可以输入十六进制字符串格式:#ffffff或ffffff)

例子:

func hexStringToUIColor (hex:String) -> UIColor {
    var cString: String = hex.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()

    if (cString.hasPrefix("#")) {
        if let range = cString.range(of: cString) {
            cString = cString.substring(from: cString.index(range.lowerBound, offsetBy: 1))
        }
    }

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

    var rgbValue: UInt32 = 0
    Scanner(string: cString).scanHexInt32(&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)
    )
}

用法:

var color1 = hexStringToUIColor("#d3d3d3")

一个伟大的Swift实现(为Xcode 7更新)使用扩展，从各种不同的答案和地方拉到一起。在结尾还需要字符串扩展名。

Use:

let hexColor = UIColor(hex: "#00FF00")

注意:我添加了一个选项，为alpha通道的标准6位十六进制值的末尾添加2个额外的数字(传入值为00-99)。如果这冒犯了你，就把它拿掉。您可以实现它来传递一个可选的alpha参数。

扩展:

extension UIColor {

    convenience init(var hex: String) {
        var alpha: Float = 100
        let hexLength = hex.characters.count
        if !(hexLength == 7 || hexLength == 9) {
            // A hex must be either 7 or 9 characters (#RRGGBBAA)
            print("improper call to 'colorFromHex', hex length must be 7 or 9 chars (#GGRRBBAA)")
            self.init(white: 0, alpha: 1)
            return
        }

        if hexLength == 9 {
            // Note: this uses String subscripts as given below
            alpha = hex[7...8].floatValue
            hex = hex[0...6]
        }

        // Establishing the rgb color
        var rgb: UInt32 = 0
        let s: NSScanner = NSScanner(string: hex)
        // Setting the scan location to ignore the leading `#`
        s.scanLocation = 1
        // Scanning the int into the rgb colors
        s.scanHexInt(&rgb)

        // Creating the UIColor from hex int
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(alpha / 100)
        )
    }
}

字符串扩展: 浮动的来源 下标源

extension String {

    /**
    Returns the float value of a string
    */
    var floatValue: Float {
        return (self as NSString).floatValue
    }

    /**
    Subscript to allow for quick String substrings ["Hello"][0...1] = "He"
    */
    subscript (r: Range<Int>) -> String {
        get {
            let start = self.startIndex.advancedBy(r.startIndex)
            let end = self.startIndex.advancedBy(r.endIndex - 1)
            return self.substringWithRange(start..<end)
        }
    }
}