Add Swift Package Manager support

.gitignore

@@ -1,3 +1,3 @@
-xcuserdata
-xcshareddata
-
+.build/
+.swiftpm/
+xcuserdata/

Package.swift

@@ -0,0 +1,24 @@
+// swift-tools-version:5.3
+
+import PackageDescription
+
+let package = Package(
+    name: "Turbolinks",
+    products: [
+        .library(name: "Turbolinks", targets: ["Turbolinks"]),
+    ],
+    targets: [
+        .target(
+            name: "Turbolinks",
+            path: "Turbolinks",
+            exclude: ["Info.plist", "Tests"],
+            resources: [.copy("WebView.js")]
+        ),
+        .testTarget(
+            name: "TurbolinksTests",
+            dependencies: ["Turbolinks"],
+            path: "Turbolinks/Tests",
+            exclude: ["Info.plist"]
+        ),
+    ]
+)

Turbolinks/Bundle.swift

@@ -0,0 +1,11 @@
+import Foundation
+
+extension Bundle {
+    static var turbolinks: Bundle {
+#if SWIFT_PACKAGE
+        return Bundle.module
+#else
+        return Bundle(for: WebView.self)
+#endif
+    }
+}

Turbolinks/VisitableView.swift

@@ -1,3 +1,4 @@
+import UIKit
 import WebKit
 
 open class VisitableView: UIView {

Turbolinks/WebView.swift

@@ -28,8 +28,7 @@ class WebView: WKWebView {
     init(configuration: WKWebViewConfiguration) {
         super.init(frame: CGRect.zero, configuration: configuration)
 
-        let bundle = Bundle(for: type(of: self))
-        let source = try! String(contentsOf: bundle.url(forResource: "WebView", withExtension: "js")!, encoding: String.Encoding.utf8)
+        let source = try! String(contentsOf: Bundle.turbolinks.url(forResource: "WebView", withExtension: "js")!, encoding: String.Encoding.utf8)
         let userScript = WKUserScript(source: source, injectionTime: .atDocumentEnd, forMainFrameOnly: true)
         configuration.userContentController.addUserScript(userScript)
         configuration.userContentController.add(self, name: "turbolinks")