Added SPM support

Package.swift

@@ -0,0 +1,29 @@
+// swift-tools-version:5.0
+import PackageDescription
+
+let package = Package(
+    name: "BlurHashKit",
+    platforms: [
+        .iOS(.v12)
+    ],
+    products: [
+        .library(name: "BlurHashKit", targets: ["BlurHashKit"]),
+    ],
+    targets: [
+        .target(name: "BlurHashKit",
+                dependencies: [],
+                path: "./Swift/BlurHashKit"
+        ),
+        .target(name: "BlurHashKitCodable",
+                dependencies: ["BlurHashKit"],
+                path: "./Swift/BlurHashKitCodable"
+        ),
+        .testTarget(name: "BlurHashTest",
+                    dependencies: [
+                        "BlurHashKit",
+                        "BlurHashKitCodable",
+                    ],
+                    path: "./Swift/BlurHashTest"
+        ),
+    ]
+)

Swift/BlurHashTest/AppDelegate.swift

@@ -5,7 +5,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
     var window: UIWindow?
 
-    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
+    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         return true
     }
 }

Swift/BlurHashTest/SimpleViewController.swift

@@ -1,4 +1,5 @@
 import UIKit
+import BlurHashKitCodable
 
 class SimpleViewController: UIViewController {
     @IBOutlet weak var originalImageView: UIImageView?