Added Swift Package (#212)

Author: yene

Package.swift

@@ -0,0 +1,21 @@
+// swift-tools-version:5.1
+
+import PackageDescription
+
+let package = Package(
+    name: "UICircularProgressRing",
+    platforms: [.iOS(.v8)],
+    products: [
+        .library(
+            name: "UICircularProgressRing",
+            targets: ["UICircularProgressRing"]),
+    ],
+    dependencies: [
+    ],
+    targets: [
+        .target(
+            name: "UICircularProgressRing",
+            dependencies: [],
+						path: "src/UICircularProgressRing"),
+    ]
+)

src/UICircularProgressRing/Extensions.swift

@@ -10,6 +10,8 @@
  * This file includes internal extensions.
  */
 
+import UIKit
+
 /// Helper extension to allow removing layer animation based on AnimationKeys enum
 extension CALayer {
     func removeAnimation(forKey key: UICircularRing.AnimationKeys) {

src/UICircularProgressRing/UICircularRingValueFormatter.swift

@@ -7,6 +7,7 @@
 //
 
 import Foundation
+import UIKit
 
 // MARK: UICircularRingValueFormatter