swift5.3 UIColor使用十六进制颜色的方法实例

//
// String.swift
// bestWhiteNoise
//
// Created by 袁超 on 2020/10/10.
//

import Foundation
import UIKit

extension String {
 /// 十六进制字符串颜色转为UIColor
 /// - Parameter alpha: 透明度
 func uicolor(alpha: CGFloat = 1.0) -> UIColor {
  // 存储转换后的数值
  var red: UInt64 = 0, green: UInt64 = 0, blue: UInt64 = 0
  var hex = self
  // 如果传入的十六进制颜色有前缀，去掉前缀
  if hex.hasPrefix("0x") || hex.hasPrefix("0X") {
   hex = String(hex[hex.index(hex.startIndex, offsetBy: 2)...])
  } else if hex.hasPrefix("#") {
   hex = String(hex[hex.index(hex.startIndex, offsetBy: 1)...])
  }
  // 如果传入的字符数量不足6位按照后边都为0处理，当然你也可以进行其它操作
  if hex.count < 6 {
   for _ in 0..<6-hex.count {
    hex += "0"
   }
  }

  // 分别进行转换
  // 红
  Scanner(string: String(hex[..<hex.index(hex.startIndex, offsetBy: 2)])).scanHexInt64(&red)
  // 绿
  Scanner(string: String(hex[hex.index(hex.startIndex, offsetBy: 2)..<hex.index(hex.startIndex, offsetBy: 4)])).scanHexInt64(&green)
  // 蓝
  Scanner(string: String(hex[hex.index(startIndex, offsetBy: 4)...])).scanHexInt64(&blue)

  return UIColor(red: CGFloat(red)/255.0, green: CGFloat(green)/255.0, blue: CGFloat(blue)/255.0, alpha: alpha)
 }
}

"5188e1".uicolor()

item.setTitleTextAttributes([NSAttributedString.Key.foregroundColor: "5188e1".uicolor()], for: .selected)