How to convert Color type to hex and vice-versa while retaining alpha information?

The below should work both on macOS and iOS with one minor change. That is, use UIColor instead of NSColor if you’re planning to use it for iOS.

import SwiftUI

extension Color {
    init(hex: String) {
        var hexSanitized = hex.trimmingCharacters(in: .whitespacesAndNewlines)
        hexSanitized = hexSanitized.replacingOccurrences(of: "#", with: "")

        var rgb: UInt64 = 0

        Scanner(string: hexSanitized).scanHexInt64(&rgb)

        let red = Double((rgb & 0xFF000000) >> 24) / 255.0
        let green = Double((rgb & 0x00FF0000) >> 16) / 255.0
        let blue = Double((rgb & 0x0000FF00) >> 8) / 255.0
        let alpha = Double(rgb & 0x000000FF) / 255.0
        
        self.init(.sRGB, red: red, green: green, blue: blue, opacity: alpha)
    }

    var hex: String {
        if let nsColor = NSColor(self).usingColorSpace(.sRGB) {
            let red = Int(nsColor.redComponent * 255)
            let green = Int(nsColor.greenComponent * 255)
            let blue = Int(nsColor.blueComponent * 255)
            let alpha = Int(nsColor.alphaComponent * 255)

            return String(format: "#%02X%02X%02X%02X", red, green, blue, alpha)
        } else {
            // Default to .gray color if NSColor conversion fails
            return "#8e8e93ff"
        }
    }
}

You can then use it like below:

var someColor: Color = Color(hex: "#FFFFFFFF") // white color with 100% opacity
var someColorHex: String = someColor.hex // white color in hexadecimal format