这是我用的。适用于6和8字符的颜色字符串，带或不带#符号。在发布时默认为黑色，在调试时用无效字符串初始化时崩溃。

extension UIColor {
    public convenience init(hex: String) {
        var r: CGFloat = 0
        var g: CGFloat = 0
        var b: CGFloat = 0
        var a: CGFloat = 1

        let hexColor = hex.replacingOccurrences(of: "#", with: "")
        let scanner = Scanner(string: hexColor)
        var hexNumber: UInt64 = 0
        var valid = false

        if scanner.scanHexInt64(&hexNumber) {
            if hexColor.count == 8 {
                r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
                g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
                b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
                a = CGFloat(hexNumber & 0x000000ff) / 255
                valid = true
            }
            else if hexColor.count == 6 {
                r = CGFloat((hexNumber & 0xff0000) >> 16) / 255
                g = CGFloat((hexNumber & 0x00ff00) >> 8) / 255
                b = CGFloat(hexNumber & 0x0000ff) / 255
                valid = true
            }
        }

        #if DEBUG
            assert(valid, "UIColor initialized with invalid hex string")
        #endif

        self.init(red: r, green: g, blue: b, alpha: a)
    }
}

用法:

UIColor(hex: "#75CC83FF")
UIColor(hex: "75CC83FF")
UIColor(hex: "#75CC83")
UIColor(hex: "75CC83")

这个答案展示了如何在Obj-C中实现。这座桥是要用的

let rgbValue = 0xFFEEDD
let r = Float((rgbValue & 0xFF0000) >> 16)/255.0
let g = Float((rgbValue & 0xFF00) >> 8)/255.0
let b = Float((rgbValue & 0xFF))/255.0
self.backgroundColor = UIColor(red:r, green: g, blue: b, alpha: 1.0)

简单的颜色扩展Swift 5/SwiftUI

例子:

let myColor = Color(hex:0xF2C94C)

代码:

import Foundation
import SwiftUI

extension UIColor {
    convenience init(hex: Int) {
        let components = (
            R: CGFloat((hex >> 16) & 0xff) / 255,
            G: CGFloat((hex >> 08) & 0xff) / 255,
            B: CGFloat((hex >> 00) & 0xff) / 255
        )
        self.init(red: components.R, green: components.G, blue: components.B, alpha: 1)
    }
}

extension Color {
    public init(hex: Int) {
        self.init(UIColor(hex: hex))
   }
}

Swift 5:你可以在Xcode中创建颜色，如下图所示:

您应该命名颜色，因为您通过名称引用了颜色。如图2所示:

斯威夫特5.0

你不能在Swift中直接使用#ffffff语法。以下是我用于网络相关项目的代码。支持alpha和三位数字。

用法示例(大写值也可以):

    let hex = "#FADE2B"  // yellow
    let color = NSColor(fromHex: hex)

支持的字符串格式:

"fff" // RGB "#fff" // #RGB "ffff" // RGBA "#ffff" // #RGBA . "ffffff" // RRGGBB . "#ffffff" // #RRGGBB . "ffffffff" // RRGGBBAA . "#ffffffff" // #RRGGBBAA .

数字代表红色，绿色，蓝色和阿尔法(像透明度)。对于iOS，用UIColor替换NSColor。

代码:

    extension NSColor {
        /// Initialises NSColor from a hexadecimal string. Color is clear if string is invalid.
        /// - Parameter fromHex: supported formats are "#RGB", "#RGBA", "#RRGGBB", "#RRGGBBAA", with or without the # character
        public convenience init(fromHex:String) {
            var r = 0, g = 0, b = 0, a = 255
            let offset = fromHex.hasPrefix("#") ? 1 : 0
            let ch = fromHex.map{$0}
            switch(ch.count - offset) {
            case 8:
                a = 16 * (ch[offset+6].hexDigitValue ?? 0) + (ch[offset+7].hexDigitValue ?? 0)
                fallthrough
            case 6:
                r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
                g = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
                b = 16 * (ch[offset+4].hexDigitValue ?? 0) + (ch[offset+5].hexDigitValue ?? 0)
                break
            case 4:
                a = 16 * (ch[offset+3].hexDigitValue ?? 0) + (ch[offset+3].hexDigitValue ?? 0)
                fallthrough
            case 3:  // Three digit #0D3 is the same as six digit #00DD33
                r = 16 * (ch[offset+0].hexDigitValue ?? 0) + (ch[offset+0].hexDigitValue ?? 0)
                g = 16 * (ch[offset+1].hexDigitValue ?? 0) + (ch[offset+1].hexDigitValue ?? 0)
                b = 16 * (ch[offset+2].hexDigitValue ?? 0) + (ch[offset+2].hexDigitValue ?? 0)
                break
            default:
                a = 0
                break
            }
            self.init(red: CGFloat(r)/255, green: CGFloat(g)/255, blue: CGFloat(b)/255, alpha: CGFloat(a)/255)
            
        }
    }
    // Author: Andrew Kingdom

授权:CC BY

我发现这比下面的复制/粘贴更整洁

选择:

您可以删除#并将其存储为32位无符号整数字面量，由0x前缀表示，即0xffffff。不过，你仍然需要代码将其转换为颜色。

如果你想要一种非编程的方式来获取颜色:打开一个颜色选择器对话框，切换到colour Sliders > RGB Sliders，并将值粘贴/输入到“Hex color #”框中。(不要粘贴#散列符号。)

这是UIColor的一个Swift扩展，它采用十六进制字符串:

import UIKit

extension UIColor {

    convenience init(hexString: String) {
        // Trim leading '#' if needed
        var cleanedHexString = hexString
        if hexString.hasPrefix("#") {
//            cleanedHexString = dropFirst(hexString) // Swift 1.2
            cleanedHexString = String(hexString.characters.dropFirst()) // Swift 2
        }

        // String -> UInt32
        var rgbValue: UInt32 = 0
        NSScanner(string: cleanedHexString).scanHexInt(&rgbValue)

        // UInt32 -> R,G,B
        let red = CGFloat((rgbValue >> 16) & 0xff) / 255.0
        let green = CGFloat((rgbValue >> 08) & 0xff) / 255.0
        let blue = CGFloat((rgbValue >> 00) & 0xff) / 255.0

        self.init(red: red, green: green, blue: blue, alpha: 1.0)
    }

}