Support Swift Package

Package.swift

@@ -0,0 +1,22 @@
+// swift-tools-version:5.1
+import PackageDescription
+
+let package = Package(
+    name: "Hue",
+    platforms: [
+        .iOS(.v8),
+        .macOS(.v10_11),
+        .tvOS(.v9),
+    ],
+    products: [
+        .library(
+            name: "Hue",
+            targets: ["Hue"]),
+    ],
+    targets: [
+        .target(
+            name: "Hue",
+            path: "Source"),
+    ],
+    swiftLanguageVersions: [.v5]
+)

README.md

@@ -136,6 +136,12 @@ To install just write into your Cartfile:
 github "hyperoslo/Hue"
 ```
 
+To install **Hue** using [Swift Package Manager](https://swift.org/package-manager) with Xcode 11, just follow the instructions at <https://developer.apple.com/documentation/swift_packages> and import the platform specific library to the project:
+
+```swift
+import Hue
+```
+
 ## Author
 
 [Hyper](http://hyper.no) made this with ❤️

Source/iOS+tvOS/UIColor+Hue.swift

@@ -1,3 +1,4 @@
+#if canImport(UIKit)
 import UIKit
 
 // MARK: - Color Builders
@@ -245,3 +246,4 @@ public extension UIColor {
     return self.add(red: color.redComponent, green: color.greenComponent, blue: color.blueComponent, alpha: color.alphaComponent)
   }
 }
+#endif

Source/iOS+tvOS/UIImage+Hue.swift

@@ -1,3 +1,4 @@
+#if canImport(UIKit)
 import UIKit
 
 class CountedColor {
@@ -174,3 +175,4 @@ extension UIImage {
     }
   }
 }
+#endif

Source/macOS/NSColor+Hue.swift

@@ -1,3 +1,4 @@
+#if canImport(AppKit)
 import AppKit
 
 // MARK: - Color Builders
@@ -258,3 +259,4 @@ public extension NSColor {
     return self.add(red: color.getRed(), green: color.getGreen(), blue: color.getBlue(), alpha: color.getAlpha())
   }
 }
+#endif

Source/macOS/NSImage+Hue.swift

@@ -1,3 +1,4 @@
+#if canImport(AppKit)
 import AppKit
 
 class CountedColor {
@@ -163,3 +164,4 @@ extension NSImage {
       detailColor    ?? (isDarkBackgound ? whiteColor : blackColor))
   }
 }
+#endif