RGBA版本Swift 3/4

我喜欢卢卡的回答，因为我认为它是最优雅的。

然而，我不希望我的颜色指定在ARGB。我宁愿RGBA +，我也需要在处理字符串的情况下，为每个频道指定1个字符“#FFFA”。

这个版本还增加了错误抛出+剥离'#'字符如果它包含在字符串中。 这是我修改后的Swift表格。

public enum ColourParsingError: Error
{
    
    case invalidInput(String)
}
extension UIColor {
    public convenience init(hexString: String) throws
    {
        let hexString = hexString.replacingOccurrences(of: "#", with: "")
        let hex = hexString.trimmingCharacters(in:NSCharacterSet.alphanumerics.inverted)
        var int = UInt32()
        Scanner(string: hex).scanHexInt32(&int)
        let a, r, g, b: UInt32
        switch hex.count 
        {
        case 3: // RGB (12-bit)
            (r, g, b,a) = ((int >> 8) * 17, (int >> 4 & 0xF) * 17, (int & 0xF) * 17,255)
        //iCSS specification in the form of #F0FA
        case 4: // RGB (24-bit)
            (r, g, b,a) = ((int >> 12) * 17, (int >> 8 & 0xF) * 17, (int >> 4 & 0xF) * 17, (int & 0xF) * 17)
        case 6: // RGB (24-bit)
            (r, g, b, a) = (int >> 16, int >> 8 & 0xFF, int & 0xFF,255)
        case 8: // ARGB (32-bit)
            (r, g, b, a) = (int >> 24, int >> 16 & 0xFF, int >> 8 & 0xFF, int & 0xFF)
        default:
            throw ColourParsingError.invalidInput("String is not a valid hex colour string: \(hexString)")
        }
        self.init(red: CGFloat(r) / 255, green: CGFloat(g) / 255, blue: CGFloat(b) / 255, alpha: CGFloat(a) / 255)
    }
}

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))
   }
}

带验证的十六进制

根据爱德华多的回答

细节

Xcode 10.0, Swift 4.2 Xcode 10.2.1 (10E1001)

解决方案

import UIKit

extension UIColor {

    convenience init(r: UInt8, g: UInt8, b: UInt8, alpha: CGFloat = 1.0) {
        let divider: CGFloat = 255.0
        self.init(red: CGFloat(r)/divider, green: CGFloat(g)/divider, blue: CGFloat(b)/divider, alpha: alpha)
    }

    private convenience init(rgbWithoutValidation value: Int32, alpha: CGFloat = 1.0) {
        self.init(
            r: UInt8((value & 0xFF0000) >> 16),
            g: UInt8((value & 0x00FF00) >> 8),
            b: UInt8(value & 0x0000FF),
            alpha: alpha
        )
    }

    convenience init?(rgb: Int32, alpha: CGFloat = 1.0) {
        if rgb > 0xFFFFFF || rgb < 0 { return nil }
        self.init(rgbWithoutValidation: rgb, alpha: alpha)
    }

    convenience init?(hex: String, alpha: CGFloat = 1.0) {
        var charSet = CharacterSet.whitespacesAndNewlines
        charSet.insert("#")
        let _hex = hex.trimmingCharacters(in: charSet)
        guard _hex.range(of: "^[0-9A-Fa-f]{6}$", options: .regularExpression) != nil else { return nil }
        var rgb: UInt32 = 0
        Scanner(string: _hex).scanHexInt32(&rgb)
        self.init(rgbWithoutValidation: Int32(rgb), alpha: alpha)
    }
}

使用

let alpha: CGFloat = 1.0

// Hex
print(UIColor(rgb: 0x4F9BF5) ?? "nil")
print(UIColor(rgb: 0x4F9BF5, alpha: alpha) ?? "nil")
print(UIColor(rgb: 5217269) ?? "nil")
print(UIColor(rgb: -5217269) ?? "nil")                  // = nil
print(UIColor(rgb: 0xFFFFFF1) ?? "nil")                 // = nil

// String
print(UIColor(hex: "4F9BF5") ?? "nil")
print(UIColor(hex: "4F9BF5", alpha: alpha) ?? "nil")
print(UIColor(hex: "#4F9BF5") ?? "nil")
print(UIColor(hex: "#4F9BF5", alpha: alpha) ?? "nil")
print(UIColor(hex: "#4F9BF56") ?? "nil")                // = nil
print(UIColor(hex: "#blabla") ?? "nil")                 // = nil

// RGB
print(UIColor(r: 79, g: 155, b: 245))
print(UIColor(r: 79, g: 155, b: 245, alpha: alpha))
//print(UIColor(r: 792, g: 155, b: 245, alpha: alpha))  // Compiler will throw an error, r,g,b = [0...255]

Xcode 13.2.1, M1, Swift 5.5

我们可以在ColorLiterals中使用Hex

输入#colorLiteral(在Xcode中，这将触发并修复与ColorLiterals相关的错误

然后点击其他

然后选择RGB滑块，你现在可以看到十六进制面板

这是一个接受十六进制字符串并返回UIColor的函数。 (你可以输入十六进制字符串格式:#ffffff或ffffff)

用法:

var color1 = hexStringToUIColor("#d3d3d3")

Swift 5:(Swift 4+)

func hexStringToUIColor (hex:String) -> UIColor {
    var cString:String = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()

    if (cString.hasPrefix("#")) {
        cString.remove(at: cString.startIndex)
    }

    if ((cString.count) != 6) {
        return UIColor.gray
    }

    var rgbValue:UInt64 = 0
    Scanner(string: cString).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)
    )
}

斯威夫特3:

func hexStringToUIColor (hex:String) -> UIColor {
    var cString:String = hex.trimmingCharacters(in: .whitespacesAndNewlines).uppercased()

    if (cString.hasPrefix("#")) {
        cString.remove(at: cString.startIndex)
    }

    if ((cString.characters.count) != 6) {
        return UIColor.gray
    }

    var rgbValue:UInt32 = 0
    Scanner(string: cString).scanHexInt32(&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)
    )
}

斯威夫特2:

func hexStringToUIColor (hex:String) -> UIColor {
    var cString:String = hex.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet() as NSCharacterSet).uppercaseString

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

    if ((cString.characters.count) != 6) {
      return UIColor.grayColor()
    }

    var rgbValue:UInt32 = 0
    NSScanner(string: cString).scanHexInt(&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)
    )
}

沙德源代码:/ gist: de147c42d7b3063ef7bc

编辑:更新代码。谢谢，Hlung, jaytrixz, Ahmad F, Kegham K和Adam Waite!

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)
    }

}