SwiftUI-十六进制字符串转颜色

创建类ColorExtension.swift
代码如下：

import SwiftUI

extension Color {
    init?(hex: String){
        let r, g, b, a: CGFloat

        if hex.hasPrefix("#") {
            let start = hex.index(hex.startIndex, offsetBy: 1)
            let hexColor = String(hex[start...])

            if hexColor.count == 6 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff0000) >> 16) / 255
                    g = CGFloat((hexNumber & 0x00ff00) >> 8) / 255
                    b = CGFloat(hexNumber & 0x0000ff) / 255
                    a = 255 / 255

                    self.init(red: Double(r), green: Double(g), blue: Double(b))
                    _ = self.opacity(Double(a))
                    return
                }
            }
        }
        return nil
    }
}

如果十六进制颜色中需要包含透明度则将代码做如下修改：

extension Color {
    init?(hex: String){
        let r, g, b, a: CGFloat

        if hex.hasPrefix("#") {
            let start = hex.index(hex.startIndex, offsetBy: 1)
            let hexColor = String(hex[start...])
            
            //从此处开始修改
            if hexColor.count == 8 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
                    g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
                    b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
                    a = CGFloat(hexNumber & 0x000000ff) / 255

                    self.init(red: Double(r), green: Double(g), blue: Double(b))
                    _ = self.opacity(Double(a))
                    return
                }
            }
        }
        return nil
    }
}

使用方法：

Text("Hello, World")
    .foregroundColor(Color(hex: "#FA651C"))