试试这个:这段代码将从十六进制颜色字符串返回UIColor

- (UIColor*)colorWithHexString:(NSString*)hex  
{  
    NSString *cString = [[hex stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];  

    // String should be 6 or 8 characters  
    if ([cString length] < 6) return [UIColor grayColor];  

    // strip 0X if it appears  
    if ([cString hasPrefix:@"0X"]) cString = [cString substringFromIndex:2];  

    if ([cString length] != 6) return  [UIColor grayColor];  

    // Separate into r, g, b substrings  
    NSRange range;  
    range.location = 0;  
    range.length = 2;  
    NSString *rString = [cString substringWithRange:range];  

    range.location = 2;  
    NSString *gString = [cString substringWithRange:range];  

    range.location = 4;  
    NSString *bString = [cString substringWithRange:range];  

    // Scan values  
    unsigned int r, g, b;  
    [[NSScanner scannerWithString:rString] scanHexInt:&r];  
    [[NSScanner scannerWithString:gString] scanHexInt:&g];  
    [[NSScanner scannerWithString:bString] scanHexInt:&b];  

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

斯威夫特版本:

extension UIColor {
    convenience init?(var hex: String) {
        hex = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString
        hex = (hex.hasPrefix("#")) ? hex.substringFromIndex(advance(hex.startIndex, 1)) : hex

        var value: UInt32 = 0
        if NSScanner(string: hex).scanHexInt(&value) {
            if count(hex) == 8 {
                self.init(red: CGFloat((value & 0xFF000000) >> 24) / 255.0,
                    green: CGFloat((value & 0x00FF0000) >> 16) / 255.0,
                    blue: CGFloat((value & 0x0000FF00) >> 8) / 255.0,
                    alpha: CGFloat((value & 0x000000FF)) / 255.0)
                return
            } else if count(hex) == 6 {
                self.init(red: CGFloat((value & 0xFF0000) >> 16) / 255.0,
                    green: CGFloat((value & 0x00FF00) >> 8) / 255.0,
                    blue: CGFloat(value & 0x0000FF) / 255.0,
                    alpha: 1.0)
                return
            }
        }
        self.init()
        return nil
    }
}

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)

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)
        }
    }
}

斯威夫特的版本。作为函数或扩展使用。

Function

  func UIColorFromRGB(colorCode: String, alpha: Float = 1.0) -> UIColor{
    var scanner = NSScanner(string:colorCode)
    var color:UInt32 = 0;
    scanner.scanHexInt(&color)
    
    let mask = 0x000000FF
    let r = CGFloat(Float(Int(color >> 16) & mask)/255.0)
    let g = CGFloat(Float(Int(color >> 8) & mask)/255.0)
    let b = CGFloat(Float(Int(color) & mask)/255.0)
    
    return UIColor(red: r, green: g, blue: b, alpha: CGFloat(alpha))
}

Extension

extension UIColor {
    convenience init(colorCode: String, alpha: Float = 1.0){
        var scanner = NSScanner(string:colorCode)
        var color:UInt32 = 0;
        scanner.scanHexInt(&color)
        
        let mask = 0x000000FF
        let r = CGFloat(Float(Int(color >> 16) & mask)/255.0)
        let g = CGFloat(Float(Int(color >> 8) & mask)/255.0)
        let b = CGFloat(Float(Int(color) & mask)/255.0)
        
        self.init(red: r, green: g, blue: b, alpha: CGFloat(alpha))
    }
}

How to call

let hexColorFromFunction = UIColorFromRGB("F4C124", alpha: 1.0)
let hexColorFromExtension = UIColor(colorCode: "F4C124", alpha: 1.0)

You can also define your Hex Color from interface builder.