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)
    }
}

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]

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.

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

张贴参考网站我刚刚找到。 它做了所有的脏工作，从HEX或RGB开始，在ObjC, Swift和Xamarin中打印出代码。

https://www.uicolor.xyz/#/hex-to-ui