項目開發(fā)中我們需要通過 16 進制顏色字符串（比如：#F0FFFF）來初始化 UIColor庆捺，或者將 UIColor 轉(zhuǎn)成 16 進制字符串打印或顯示出來。下面是如何實現(xiàn)屁魏。

1.擴展 UIColor

為方便使用滔以，我們首先對 UIColor 進行擴展（UIColor+Ext.swift），增加相關(guān)的轉(zhuǎn)換方法和屬性

import UIKit
 
extension UIColor {
     
    // Hex String -> UIColor
    convenience init(hexString: String) {
        let hexString = hexString.trimmingCharacters(in: .whitespacesAndNewlines)
        let scanner = Scanner(string: hexString)
         
        if hexString.hasPrefix("#") {
            scanner.scanLocation = 1
        }
         
        var color: UInt32 = 0
        scanner.scanHexInt32(&color)
         
        let mask = 0x000000FF
        let r = Int(color >> 16) & mask
        let g = Int(color >> 8) & mask
        let b = Int(color) & mask
         
        let red   = CGFloat(r) / 255.0
        let green = CGFloat(g) / 255.0
        let blue  = CGFloat(b) / 255.0
         
        self.init(red: red, green: green, blue: blue, alpha: 1)
    }
     
    // UIColor -> Hex String
    var hexString: String? {
        var red: CGFloat = 0
        var green: CGFloat = 0
        var blue: CGFloat = 0
        var alpha: CGFloat = 0
         
        let multiplier = CGFloat(255.999999)
         
        guard self.getRed(&red, green: &green, blue: &blue, alpha: &alpha) else {
            return nil
        }
         
        if alpha == 1.0 {
            return String(
                format: "#%02lX%02lX%02lX",
                Int(red * multiplier),
                Int(green * multiplier),
                Int(blue * multiplier)
            )
        }
        else {
            return String(
                format: "#%02lX%02lX%02lX%02lX",
                Int(red * multiplier),
                Int(green * multiplier),
                Int(blue * multiplier),
                Int(alpha * multiplier)
            )
        }
    }
}

2.使用方法

import UIKit
 
class ViewController: UIViewController {
     
    override func viewDidLoad() {
        super.viewDidLoad()
         
        // 16進制顏色 -> UIColor
        let color = UIColor(hexString: "#FFFFFF")
        print("UIColor：", color)
         
        // UIColor -> 16進制顏色
        let hexString = color.hexString
        print("16進制顏色值：", hexString ?? "")
    }
}