Add spm

Package.swift

@@ -0,0 +1,21 @@
+// swift-tools-version:5.1
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "QRCodeReader",
+    platforms: [
+        .iOS(.v10)
+    ],
+    products: [
+        .library(
+            name: "QRCodeReader",
+            targets: ["QRCodeReader"]),
+    ],
+    targets: [
+        .target(
+            name: "QRCodeReader",
+            path: "QRCodeReader/Classes"),
+    ]
+)