有cocoapod支持，这很好

https://github.com/mRs-/HexColors

// with hash
NSColor *colorWithHex = [NSColor colorWithHexString:@"#ff8942" alpha:1];

// wihtout hash
NSColor *secondColorWithHex = [NSColor colorWithHexString:@"ff8942" alpha:1];

// short handling
NSColor *shortColorWithHex = [NSColor colorWithHexString:@"fff" alpha:1]

在swift中，我用以下方法创建了一个类扩展，将十六进制代码转换为UIColor。

extension UIColor {  
  convenience init(R: CGFloat, G: CGFloat, B: CGFloat, alpha: CGFloat) {
    self.init(red: R/255.0, green: G/255.0, blue: B/255.0, alpha: alpha)
  }

  class func colorWithHex(hex: UInt, alpha: CGFloat) -> UIColor {
    return UIColor(R: CGFloat((hex & 0xFF0000) >> 16), G: CGFloat((hex & 0x00FF00) >> 8), B: CGFloat(hex & 0x0000FF), alpha: alpha)
  }
}

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
    }
}

我已经找到了一个与Android使用的十六进制格式字符串100%兼容的解决方案，我发现这在进行跨平台移动开发时非常有用。它让我在两个平台上都使用一种颜色。您可以在没有归属的情况下随意重用，如果您愿意，也可以在Apache许可下重用。

#import "UIColor+HexString.h"

@interface UIColor(HexString)

+ (UIColor *) colorWithHexString: (NSString *) hexString;
+ (CGFloat) colorComponentFrom: (NSString *) string start: (NSUInteger) start length: (NSUInteger) length;

@end


@implementation UIColor(HexString)

+ (UIColor *) colorWithHexString: (NSString *) hexString {
    NSString *colorString = [[hexString stringByReplacingOccurrencesOfString: @"#" withString: @""] uppercaseString];
    CGFloat alpha, red, blue, green;
    switch ([colorString length]) {
        case 3: // #RGB
            alpha = 1.0f;
            red   = [self colorComponentFrom: colorString start: 0 length: 1];
            green = [self colorComponentFrom: colorString start: 1 length: 1];
            blue  = [self colorComponentFrom: colorString start: 2 length: 1];
            break;
        case 4: // #ARGB
            alpha = [self colorComponentFrom: colorString start: 0 length: 1];
            red   = [self colorComponentFrom: colorString start: 1 length: 1];
            green = [self colorComponentFrom: colorString start: 2 length: 1];
            blue  = [self colorComponentFrom: colorString start: 3 length: 1];          
            break;
        case 6: // #RRGGBB
            alpha = 1.0f;
            red   = [self colorComponentFrom: colorString start: 0 length: 2];
            green = [self colorComponentFrom: colorString start: 2 length: 2];
            blue  = [self colorComponentFrom: colorString start: 4 length: 2];                      
            break;
        case 8: // #AARRGGBB
            alpha = [self colorComponentFrom: colorString start: 0 length: 2];
            red   = [self colorComponentFrom: colorString start: 2 length: 2];
            green = [self colorComponentFrom: colorString start: 4 length: 2];
            blue  = [self colorComponentFrom: colorString start: 6 length: 2];                      
            break;
        default:
            [NSException raise:@"Invalid color value" format: @"Color value %@ is invalid.  It should be a hex value of the form #RBG, #ARGB, #RRGGBB, or #AARRGGBB", hexString];
            break;
    }
    return [UIColor colorWithRed: red green: green blue: blue alpha: alpha];
}

+ (CGFloat) colorComponentFrom: (NSString *) string start: (NSUInteger) start length: (NSUInteger) length {
    NSString *substring = [string substringWithRange: NSMakeRange(start, length)];
    NSString *fullHex = length == 2 ? substring : [NSString stringWithFormat: @"%@%@", substring, substring];
    unsigned hexComponent;
    [[NSScanner scannerWithString: fullHex] scanHexInt: &hexComponent];
    return hexComponent / 255.0;
}

@end 

迅速:

extension UIColor {
    convenience init?(hexString: String?) {
        let input: String! = (hexString ?? "")
            .replacingOccurrences(of: "#", with: "")
            .uppercased()
        var alpha: CGFloat = 1.0
        var red: CGFloat = 0
        var blue: CGFloat = 0
        var green: CGFloat = 0
        switch (input.count) {
        case 3 /* #RGB */:
            red = Self.colorComponent(from: input, start: 0, length: 1)
            green = Self.colorComponent(from: input, start: 1, length: 1)
            blue = Self.colorComponent(from: input, start: 2, length: 1)
            break
        case 4 /* #ARGB */:
            alpha = Self.colorComponent(from: input, start: 0, length: 1)
            red = Self.colorComponent(from: input, start: 1, length: 1)
            green = Self.colorComponent(from: input, start: 2, length: 1)
            blue = Self.colorComponent(from: input, start: 3, length: 1)
            break
        case 6 /* #RRGGBB */:
            red = Self.colorComponent(from: input, start: 0, length: 2)
            green = Self.colorComponent(from: input, start: 2, length: 2)
            blue = Self.colorComponent(from: input, start: 4, length: 2)
            break
        case 8 /* #AARRGGBB */:
            alpha = Self.colorComponent(from: input, start: 0, length: 2)
            red = Self.colorComponent(from: input, start: 2, length: 2)
            green = Self.colorComponent(from: input, start: 4, length: 2)
            blue = Self.colorComponent(from: input, start: 6, length: 2)
            break
        default:
            NSException.raise(NSExceptionName("Invalid color value"), format: "Color value \"%@\" is invalid.  It should be a hex value of the form #RBG, #ARGB, #RRGGBB, or #AARRGGBB", arguments:getVaList([hexString ?? ""]))
        }
        self.init(red: red, green: green, blue: blue, alpha: alpha)
    }
    
    static func colorComponent(from string: String!, start: Int, length: Int) -> CGFloat {
        let substring = (string as NSString)
            .substring(with: NSRange(location: start, length: length))
        let fullHex = length == 2 ? substring : "\(substring)\(substring)"
        var hexComponent: UInt64 = 0
        Scanner(string: fullHex)
            .scanHexInt64(&hexComponent)
        return CGFloat(Double(hexComponent) / 255.0)
    }
}

我发现最简单的方法是使用宏。只要把它包括在你的标题中，它就可以在你的整个项目中使用。

#define UIColorFromRGB(rgbValue) [UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 green:((float)((rgbValue & 0xFF00) >> 8))/255.0 blue:((float)(rgbValue & 0xFF))/255.0 alpha:1.0]

Uicolor宏十六进制值

这段代码的格式化版本:

#define UIColorFromRGB(rgbValue) \
[UIColor colorWithRed:((float)((rgbValue & 0xFF0000) >> 16))/255.0 \
                green:((float)((rgbValue & 0x00FF00) >>  8))/255.0 \
                 blue:((float)((rgbValue & 0x0000FF) >>  0))/255.0 \
                alpha:1.0]

用法:

label.textColor = UIColorFromRGB(0xBC1128);

迅速:

static func UIColorFromRGB(_ rgbValue: Int) -> UIColor! {
    return UIColor(
        red: CGFloat((Float((rgbValue & 0xff0000) >> 16)) / 255.0),
        green: CGFloat((Float((rgbValue & 0x00ff00) >> 8)) / 255.0),
        blue: CGFloat((Float((rgbValue & 0x0000ff) >> 0)) / 255.0),
        alpha: 1.0)
}

抛光扩展从原来的答案@Tom 请随意在这里更新代码

extension UIColor{
    convenience init (hexString:String) {
        var cleanString:String = hexString.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).uppercaseString

        if (cleanString.hasPrefix("#")) {
            cleanString = cleanString.substringFromIndex(cleanString.startIndex.advancedBy(1))
        }

        if (cleanString.characters.count != 6) {
            self.init()
        }
        else{
            var rgbValue = UInt32()
            let scanner = NSScanner(string: cleanString)
            scanner.scanHexInt(&rgbValue)

            self.init(
                red: CGFloat((rgbValue & 0xFF0000) >> 16)/255.0,
                green: CGFloat((rgbValue & 0xFF00) >> 8)/255.0,
                blue: CGFloat(rgbValue & 0xFF)/255.0,
                alpha: 1.0)
        }
    }
}