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:

你可以在swift 5中使用它

斯威夫特5

import UIKit

extension UIColor {
    static 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: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)
        )
    }
}

UIColor扩展，这将大大帮助你!(4.0版本:斯威夫特)

import UIKit
extension UIColor {
/// rgb颜色
convenience init(r: CGFloat, g: CGFloat, b: CGFloat) {
    self.init(red: r/255.0 ,green: g/255.0 ,blue: b/255.0 ,alpha:1.0)
}

/// 纯色（用于灰色）
convenience init(gray: CGFloat) {
    self.init(red: gray/255.0 ,green: gray/255.0 ,blue: gray/255.0 ,alpha:1.0)
}
/// 随机色
class func randomCGColor() -> UIColor {
    return UIColor(r: CGFloat(arc4random_uniform(256)), g: CGFloat(arc4random_uniform(256)), b: CGFloat(arc4random_uniform(256)))
}

/// hex颜色-Int
convenience init(hex:Int, alpha:CGFloat = 1.0) {
    self.init(
        red:   CGFloat((hex & 0xFF0000) >> 16) / 255.0,
        green: CGFloat((hex & 0x00FF00) >> 8)  / 255.0,
        blue:  CGFloat((hex & 0x0000FF) >> 0)  / 255.0,
        alpha: alpha
    )
}
/// hex颜色-String
convenience init(hexString: String){
    var red:   CGFloat = 0.0
    var green: CGFloat = 0.0
    var blue:  CGFloat = 0.0
    var alpha: CGFloat = 1.0
    let scanner = Scanner(string: hexString)
    var hexValue: CUnsignedLongLong = 0
    if scanner.scanHexInt64(&hexValue) {
        switch (hexString.characters.count) {
        case 3:
            red   = CGFloat((hexValue & 0xF00) >> 8)       / 15.0
            green = CGFloat((hexValue & 0x0F0) >> 4)       / 15.0
            blue  = CGFloat(hexValue & 0x00F)              / 15.0
        case 4:
            red   = CGFloat((hexValue & 0xF000) >> 12)     / 15.0
            green = CGFloat((hexValue & 0x0F00) >> 8)      / 15.0
            blue  = CGFloat((hexValue & 0x00F0) >> 4)      / 15.0
            alpha = CGFloat(hexValue & 0x000F)             / 15.0
        case 6:
            red   = CGFloat((hexValue & 0xFF0000) >> 16)   / 255.0
            green = CGFloat((hexValue & 0x00FF00) >> 8)    / 255.0
            blue  = CGFloat(hexValue & 0x0000FF)           / 255.0
        case 8:
            alpha = CGFloat((hexValue & 0xFF000000) >> 24) / 255.0
            red   = CGFloat((hexValue & 0x00FF0000) >> 16) / 255.0
            green = CGFloat((hexValue & 0x0000FF00) >> 8)  / 255.0
            blue  = CGFloat(hexValue & 0x000000FF)         / 255.0
        default:
            log.info("Invalid RGB string, number of characters after '#' should be either 3, 4, 6 or 8")
        }
    } else {
        log.error("Scan hex error")
    }
    self.init(red:red, green:green, blue:blue, alpha:alpha)
}}

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)

extension UIColor {

    convenience init(r: CGFloat, g: CGFloat, b: CGFloat, a: CGFloat = 1) {
        self.init(red: r/255, green: g/255, blue: b/255, alpha: a)
    }

    convenience init(hex: Int, alpha: CGFloat = 1) {
        self.init(r: CGFloat((hex >> 16) & 0xff), g: CGFloat((hex >> 08) & 0xff), b: CGFloat((hex >> 00) & 0xff), a: alpha)
    }
}