Added SwiftUI system colors extension

Package.swift

@@ -9,14 +9,15 @@ let package = Package(
         .macOS(.v10_12),
     ],
     products: [
-        .library(name: "Rainbow", targets: ["Rainbow"]),
+        .library(name: "Rainbow", targets: ["Rainbow", "RainbowSwiftUI"]),
     ],
     dependencies: [
         .package(url: "https://github.com/Quick/Quick", .upToNextMajor(from: "2.2.0")),
         .package(url: "https://github.com/Quick/Nimble",  .upToNextMajor(from: "8.0.7")),
     ],
     targets: [
-        .target(name: "Rainbow" ),
+        .target(name: "Rainbow"),
+        .target(name: "RainbowSwiftUI"),
         .testTarget(name: "RainbowTests", dependencies: [
             "Rainbow",
             "Quick",

Sources/Rainbow/RainbowColor+Hex.swift

@@ -96,9 +96,13 @@ extension RainbowColor {
         var blue: CGFloat = 0
         var alpha: CGFloat = 0
 
+        #if canImport(AppKit)
         if let color = usingColorSpace(.extendedSRGB) {
             color.getRed(&red, green: &green, blue: &blue, alpha: &alpha)
         }
+        #elseif canImport(UIKit)
+        getRed(&red, green: &green, blue: &blue, alpha: &alpha)
+        #endif
 
         var rgb = 0
         let redI = (Int)(red * 0xFF)

Sources/RainbowSwiftUI/Color+SystemColors.swift

@@ -0,0 +1,242 @@
+#if canImport(SwiftUI)
+import SwiftUI
+#if canImport(UIKit)
+import UIKit
+#endif
+
+@available(iOS 13.0, OSX 10.15, *)
+extension Color {
+
+    public static var label: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.label)
+        #elseif canImport(AppKit)
+        return Color(NSColor.labelColor)
+        #endif
+    }
+
+    public static var secondaryLabel: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.secondaryLabel)
+        #elseif canImport(AppKit)
+        return Color(NSColor.secondaryLabelColor)
+        #endif
+    }
+
+    public static var tertiaryLabel: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.tertiaryLabel)
+        #elseif canImport(AppKit)
+        return Color(NSColor.tertiaryLabelColor)
+        #endif
+    }
+
+    public static var quaternaryLabel: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.quaternaryLabel)
+        #elseif canImport(AppKit)
+        return Color(NSColor.quaternaryLabelColor)
+        #endif
+    }
+
+    public static var systemFill: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemFill)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemRed)
+        #endif
+    }
+
+    public static var secondarySystemFill: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.secondarySystemFill)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemRed)
+        #endif
+    }
+
+    public static var tertiarySystemFill: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.tertiarySystemFill)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemRed)
+        #endif
+    }
+
+    public static var quaternarySystemFill: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.quaternarySystemFill)
+        #elseif canImport(AppKit)
+        return Color(NSColor.quaternaryLabelColor)
+        #endif
+    }
+
+    public static var systemBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var secondarySystemBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.secondarySystemBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var tertiarySystemBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.tertiarySystemBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var systemGroupedBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGroupedBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var secondarySystemGroupedBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.secondarySystemGroupedBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var tertiarySystemGroupedBackground: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.tertiarySystemGroupedBackground)
+        #elseif canImport(AppKit)
+        return Color(NSColor.windowBackgroundColor)
+        #endif
+    }
+
+    public static var systemRed: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemRed)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemRed)
+        #endif
+    }
+
+    public static var systemBlue: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemBlue)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemBlue)
+        #endif
+    }
+
+    public static var systemPink: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemPink)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemPink)
+        #endif
+    }
+
+    public static var systemTeal: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemTeal)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemTeal)
+        #endif
+    }
+
+    public static var systemGreen: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGreen)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGreen)
+        #endif
+    }
+
+    public static var systemIndigo: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemIndigo)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemIndigo)
+        #endif
+    }
+
+    public static var systemOrange: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemOrange)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemOrange)
+        #endif
+    }
+
+    public static var systemPurple: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemPurple)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemPurple)
+        #endif
+    }
+
+    public static var systemYellow: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemYellow)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemYellow)
+        #endif
+    }
+
+    public static var systemGray: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+
+    public static var systemGray2: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray2)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+
+    public static var systemGray3: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray3)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+
+    public static var systemGray4: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray4)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+
+    public static var systemGray5: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray5)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+
+    public static var systemGray6: Color {
+        #if canImport(UIKit)
+        return Color(UIColor.systemGray6)
+        #elseif canImport(AppKit)
+        return Color(NSColor.systemGray)
+        #endif
+    }
+}
+#endif