Added SPM Support (#60)

- Added Package.swift
- Updated README.md with SPM instructions
- Updated .gitignore for swiftpm folder

.gitignore

@@ -23,3 +23,4 @@ xcuserdata
 ## Obj-C/Swift specific
 *.hmap
 *.ipa
+.swiftpm/

Package.swift

@@ -0,0 +1,14 @@
+// swift-tools-version:4.1
+
+import PackageDescription
+
+let package = Package(
+    name: "SwCrypt",
+    products: [
+        .library(name: "SwCrypt", targets: ["SwCrypt"])
+    ],
+    targets: [
+        .target(name: "SwCrypt", path: "SwCrypt"),
+        .testTarget(name: "SwCryptTests", dependencies: ["SwCrypt"], path: "SwCryptTests")
+    ]
+)

README.md

@@ -148,6 +148,17 @@ Just copy [SwCrypt.swift](https://github.com/soyersoyer/SwCrypt/blob/master/SwCr
 
 [CocoaPods]: https://cocoapods.org
 [CocoaPods Installation]: https://guides.cocoapods.org/using/getting-started.html#getting-started
+
+### Swift Package Manager
+SPM is built into new versions of Xcode. To install SwCrypt with SPM:
+
+1. Open your project in Xcode
+
+2. Click "File" -> "Swift Packages" -> "Add Package Dependency..."
+
+3. Paste the following URL: https://github.com/soyersoyer/SwCrypt
+
+4. Click "Next" -> "Next" -> "Finish"
 
 
 Inspired from