Support named assets via enum values (to avoid string literals).

Color+Assets.swift

import Foundation
import SwiftUI

/// Extend Color to support named assets
extension Color {
    
    enum Assets: String, RawRepresentable {
        case appTextColor
        /// Place all your color assets here...the enum case should equal to the name you use in your Asset library
    }
    
    init(asset: Color.Assets) {
        self.init(asset.rawValue)
    }

}

/// Extend UIColor to support named assets
extension UIColor {
    convenience init(asset: Color.Assets) {
        // Force unwrap okay because we are sure that Color.Assets are available
        self.init(named: asset.rawValue)!
    }
}