A better way to store colors in a Realm database. Add a Color property to a Realm model the same way as a numeric value type (including RealmOptional). This could be cleaned up once Realm supports signed integers.

RealmColor.swift

//
//  RealmColor.swift
//
//  Created by HT154 on 11/19/16.
//  Copyright © 2016 HT154. All rights reserved.
//

import Cocoa
import RealmSwift
import SpriteKit

public typealias Color = Int32

extension Color {

    private var uint: UInt32 {
        get { return UInt32(bitPattern: self) }
        set { self = Int32(bitPattern: newValue) }
    }

    private init(_ raw: UInt32) {
        self = Int32(bitPattern: raw)
    }

    public init(_ r: UInt8, _ g: UInt8, _ b: UInt8, _ a: UInt8 = 0xff) {
        self.init((UInt32(r) << 24) | (UInt32(g) << 16) | (UInt32(b) << 8) | (UInt32(a) << 0))
    }

    public var r: UInt8 {
        get { return UInt8(uint >> 24) }
        set { uint = (uint & 0x00ffffff) | (UInt32(newValue) << 24) }
    }

    public var g: UInt8 {
        get { return UInt8(uint >> 16) }
        set { uint = (uint & 0xff00ffff) | (UInt32(newValue) << 16) }
    }

    public var b: UInt8 {
        get { return UInt8(uint >> 8) }
        set { uint = (uint & 0xffff00ff) | (UInt32(newValue) << 8) }
    }

    public var a: UInt8 {
        get { return UInt8(uint >> 0) }
        set { uint = (uint & 0xffffff00) | (UInt32(newValue) << 0) }
    }

    public var hexCode: String {
        get {
            return "#" + String(format: "%02dx%02dx%02dx", r, g, b) + (a == 0xff ? "" : String(format: "%02dx", a))
        }
        set {
            var hex = newValue.trimmingCharacters(in: .whitespacesAndNewlines)
            if hex.hasPrefix("#") {
                hex = hex.substring(from: hex.index(after: hex.startIndex))
            }

            if (hex.range(of: "(^[0-9A-Fa-f]{6}$)|(^[0-9A-Fa-f]{3}$)|(^[0-9A-Fa-f]{8}$)|(^[0-9A-Fa-f]{4}$)", options: [.regularExpression]) != nil) {
                var r: UInt8, g: UInt8, b: UInt8, a: UInt8

                if hex.characters.count > 4 {
                    r = UInt8(Scanner(string: hex[0..<2]).scanHexInt()!) & 0xff
                    g = UInt8(Scanner(string: hex[2..<4]).scanHexInt()!) & 0xff
                    b = UInt8(Scanner(string: hex[4..<6]).scanHexInt()!) & 0xff

                    if hex.characters.count % 4 == 0 {
                        a = UInt8(Scanner(string: hex[6..<8]).scanHexInt()!) & 0xff
                    } else {
                        a = 0xff
                    }
                } else {
                    r = UInt8(Scanner(string: hex[0]).scanHexInt()!) & 0xf
                    g = UInt8(Scanner(string: hex[1]).scanHexInt()!) & 0xf
                    b = UInt8(Scanner(string: hex[2]).scanHexInt()!) & 0xf

                    if hex.characters.count % 4 == 0 {
                        a = UInt8(Scanner(string: hex[3]).scanHexInt()!) & 0xf
                    } else {
                        a = 0xf
                    }

                    r |= r << 4; g |= g << 4; b |= b << 4; a |= a << 4
                }

                self = Color((UInt32(r) << 24) | (UInt32(g) << 16) | (UInt32(b) << 8) | (UInt32(a) << 0))
            }
        }
    }

    public var skColor: SKColor {
        return SKColor(red: CGFloat(r) / 255, green: CGFloat(g) / 255, blue: CGFloat(b) / 255, alpha: CGFloat(a) / 255)
    }

}