Add SPM support

Package.swift

@@ -0,0 +1,26 @@
+// swift-tools-version:5.3
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "BTNavigationDropdownMenu",
+    platforms: [
+        .iOS(.v9)
+    ],
+    products: [
+        .library(
+            name: "BTNavigationDropdownMenu",
+            targets: ["BTNavigationDropdownMenu"]
+        )
+    ],
+    targets: [
+        .target(
+            name: "BTNavigationDropdownMenu",
+            path: "Source",
+            resources: [
+                .copy("BTNavigationDropdownMenu.bundle")
+            ]
+        )
+    ]
+)

README.md

@@ -41,6 +41,15 @@ github "PhamBaTho/BTNavigationDropdownMenu" ~> 0.7
 
 Run `carthage update` to build the framework and drag the built `BTNavigationDropdownMenu.framework` into your Xcode project.
 
+### Swift Package Manager
+Once you have your Swift package set up, adding BTNavigationDropdownMenu as a dependency is as easy as adding it to the dependencies value of your Package.swift.
+
+```swift
+dependencies: [
+    .package(url: "https://github.com/PhamBaTho/BTNavigationDropdownMenu.git", .upToNextMajor(from: "1.0"))
+]
+```
+
 ## Usage
 ### Instantiate
 Start by creating an Array that contains strings as **elements of a dropdown list**:

Source/Internal/BTConfiguration.swift

@@ -46,7 +46,11 @@ final class BTConfiguration {
 
     init() {
         // Path for image
-        let bundle = Bundle(for: BTConfiguration.self)
+        var bundle = Bundle(for: BTConfiguration.self)
+        // Get own resources bundle for SPM case
+        if let packageBundle = bundle.url(forResource: "BTNavigationDropdownMenu_BTNavigationDropdownMenu", withExtension: "bundle").flatMap({ Bundle(url: $0) }) {
+            bundle = packageBundle
+        }
         let url = bundle.url(forResource: "BTNavigationDropdownMenu", withExtension: "bundle")
         let imageBundle = Bundle(url: url!)
         let checkMarkImagePath = imageBundle?.path(forResource: "checkmark_icon", ofType: "png")