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

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)
}

斯威夫特4

你可以像这样在扩展中创建一个非常方便的构造函数:

extension UIColor {
    convenience init(hexString: String, alpha: CGFloat = 1.0) {
        var hexInt: UInt32 = 0
        let scanner = Scanner(string: hexString)
        scanner.charactersToBeSkipped = CharacterSet(charactersIn: "#")
        scanner.scanHexInt32(&hexInt)

        let red = CGFloat((hexInt & 0xff0000) >> 16) / 255.0
        let green = CGFloat((hexInt & 0xff00) >> 8) / 255.0
        let blue = CGFloat((hexInt & 0xff) >> 0) / 255.0
        let alpha = alpha

        self.init(red: red, green: green, blue: blue, alpha: alpha)
    }
}

以后再用

let color = UIColor(hexString: "#AABBCCDD")

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

我找到了一个很好的UIColor类别，UIColor+PXExtensions。

用法:UIColor *mycolor = [UIColor pxColorWithHexValue:@"#BADA55"];

而且，为了防止链接到我的要点失败，这里是实际的实现代码:

//
//  UIColor+PXExtensions.m
//

#import "UIColor+UIColor_PXExtensions.h"

@implementation UIColor (UIColor_PXExtensions)

+ (UIColor*)pxColorWithHexValue:(NSString*)hexValue
{
    //Default
    UIColor *defaultResult = [UIColor blackColor];

    //Strip prefixed # hash
    if ([hexValue hasPrefix:@"#"] && [hexValue length] > 1) {
        hexValue = [hexValue substringFromIndex:1];
    }

    //Determine if 3 or 6 digits
    NSUInteger componentLength = 0;
    if ([hexValue length] == 3)
    {
        componentLength = 1;
    }
    else if ([hexValue length] == 6)
    {
        componentLength = 2;
    }
    else
    {
        return defaultResult;
    }

    BOOL isValid = YES;
    CGFloat components[3];

    //Seperate the R,G,B values
    for (NSUInteger i = 0; i < 3; i++) {
        NSString *component = [hexValue substringWithRange:NSMakeRange(componentLength * i, componentLength)];
        if (componentLength == 1) {
            component = [component stringByAppendingString:component];
        }
        NSScanner *scanner = [NSScanner scannerWithString:component];
        unsigned int value;
        isValid &= [scanner scanHexInt:&value];
        components[i] = (CGFloat)value / 256.0f;
    }

    if (!isValid) {
        return defaultResult;
    }

    return [UIColor colorWithRed:components[0]
                           green:components[1]
                            blue:components[2]
                           alpha:1.0];
}

@end

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