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];  
}

使用这个类别:

在文件UIColor+Hexadecimal.h中

#import <UIKit/UIKit.h>

@interface UIColor(Hexadecimal)

+ (UIColor *)colorWithHexString:(NSString *)hexString;

@end

在文件UIColor+Hexadecimal.m中

#import "UIColor+Hexadecimal.h"

@implementation UIColor(Hexadecimal)

+ (UIColor *)colorWithHexString:(NSString *)hexString {
    unsigned rgbValue = 0;
    NSScanner *scanner = [NSScanner scannerWithString:hexString];
    [scanner setScanLocation:1]; // bypass '#' character
    [scanner scanHexInt:&rgbValue];

    return [UIColor colorWithRed:((rgbValue & 0xFF0000) >> 16)/255.0 green:((rgbValue & 0xFF00) >> 8)/255.0 blue:(rgbValue & 0xFF)/255.0 alpha:1.0];
}

@end

你想在课堂上使用它:

#import "UIColor+Hexadecimal.h"

and:

[UIColor colorWithHexString:@"#6e4b4b"];

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等价于@Tom的答案，尽管接收RGBA Int值以支持透明度:

func colorWithHex(aHex: UInt) -> UIColor
{
    return UIColor(red: CGFloat((aHex & 0xFF000000) >> 24) / 255,
        green: CGFloat((aHex & 0x00FF0000) >> 16) / 255,
        blue: CGFloat((aHex & 0x0000FF00) >> 8) / 255,
        alpha: CGFloat((aHex & 0x000000FF) >> 0) / 255)
}

//usage
var color = colorWithHex(0x7F00FFFF)

如果你想从string中使用它，你可以使用strtoul:

var hexString = "0x7F00FFFF"

let num = strtoul(hexString, nil, 16)

var colorFromString = colorWithHex(num)

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

 You Can Get UIColor From String Code Like
   circularSpinner.fillColor = [self getUIColorObjectFromHexString:@"27b8c8" alpha:9];

 //Function For Hex Color Use
    - (unsigned int)intFromHexString:(NSString *)hexStr
    {
        unsigned int hexInt = 0;

        // Create scanner
        NSScanner *scanner = [NSScanner scannerWithString:hexStr];

        // Tell scanner to skip the # character
        [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"#"]];

        // Scan hex value
        [scanner scanHexInt:&hexInt];

        return hexInt;
    }




    - (UIColor *)getUIColorObjectFromHexString:(NSString *)hexStr alpha:(CGFloat)alpha
    {
        // Convert hex string to an integer
        unsigned int hexint = [self intFromHexString:hexStr];

        // Create color object, specifying alpha as well
        UIColor *color =
        [UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255
                        green:((CGFloat) ((hexint & 0xFF00) >> 8))/255
                         blue:((CGFloat) (hexint & 0xFF))/255
                        alpha:alpha];

        return color;
    }

    /Function For Hex Color Use
    - (unsigned int)intFromHexString:(NSString *)hexStr
    {
        unsigned int hexInt = 0;

        // Create scanner
        NSScanner *scanner = [NSScanner scannerWithString:hexStr];

        // Tell scanner to skip the # character
        [scanner setCharactersToBeSkipped:[NSCharacterSet characterSetWithCharactersInString:@"#"]];

        // Scan hex value
        [scanner scanHexInt:&hexInt];

        return hexInt;
    }




    - (UIColor *)getUIColorObjectFromHexString:(NSString *)hexStr alpha:(CGFloat)alpha
    {
        // Convert hex string to an integer
        unsigned int hexint = [self intFromHexString:hexStr];

        // Create color object, specifying alpha as well
        UIColor *color =
        [UIColor colorWithRed:((CGFloat) ((hexint & 0xFF0000) >> 16))/255
                        green:((CGFloat) ((hexint & 0xFF00) >> 8))/255
                         blue:((CGFloat) (hexint & 0xFF))/255
                        alpha:alpha];

        return color;
    }