Color.swift

public enum Color: UInt32, ColorRepresentable {

    case secondary = 0x9B9B9B
    case accent = 0x0083C1
    case success = 0x7ED321
    
    public enum Complete: UInt32, ColorRepresentable {
        case background = 0x374162
    }
}

protocol ColorRepresentable: RawRepresentable { }

extension ColorRepresentable where Self.RawValue == UInt32  {
    
    /// Returns opaque color
    var opaque: UIColor {
        return UIColor(rgb: self.rawValue)
    }
    
    /** 
     Returns color with alpha component.
     
     - parameter alpha: Alpha component of color.
     
     - returns: New color.
     */
    func alpha(_ alpha: CGFloat) -> UIColor {
        return self.opaque.withAlphaComponent(alpha)
    }
}

extension UIColor {
    
    // MARK: -
    // MARK: Subtypes
    
    enum Channel: UInt32 {
        case red = 3
        case green = 2
        case blue = 1
        case alpha = 0
    }
    
    /**
     Creates opaque color with RGB hex value.
     
     - parameter rgb: Color in hex UInt32 value of form 00RRGGBB, where each letter pair is 1 byte.
     
     - return: New color.
     */
    convenience init(rgb: UInt32) {
        self.init(rgba: (rgb << 😍 | 0xFF)
    }
    
    /**
     Creates opaque color with RGBA hex value.
     
     - parameter rgb: Color in hex UInt32 value of form RRGGBBAA, where each letter pair is 1 byte.
     
     - return: New color.
     */
    convenience init(rgba: UInt32) {
        let channel: (Channel) -> CGFloat = { CGFloat((rgba >> ($0.rawValue * 8)) & 0xFF) / 255.0 }
        
        self.init(red: channel(.red), green: channel(.green), blue: channel(.blue), alpha: channel(.alpha))
    }
}