Support watchOS 9

Package.swift

@@ -3,7 +3,7 @@ import PackageDescription
 
 let package = Package(
     name: "Zephyr",
-    platforms: [.iOS(.v11), .tvOS(.v11)],
+    platforms: [.iOS(.v11), .tvOS(.v11), .watchOS("9.0")],
     products: [.library(name: "Zephyr", targets: ["Zephyr"])],
     targets: [.target(name: "Zephyr", path: "Sources")],  
     swiftLanguageVersions: [.v5]

Sources/Zephyr.swift

@@ -9,6 +9,8 @@
 import Foundation
 #if os(iOS) || os(tvOS)
 import UIKit
+#elseif os(watchOS)
+import WatchKit
 #endif
 
 /// Enumerates the Local (`UserDefaults`) and Remote (`NSUNSUbiquitousKeyValueStore`) data stores
@@ -234,6 +236,14 @@ private extension Zephyr {
                                                name: UIApplication.willEnterForegroundNotification,
                                                object: nil)
         #endif
+
+        #if os(watchOS)
+        if #available(watchOS 9.0, *) {
+            NotificationCenter.default.addObserver(self, selector: #selector(willEnterForeground(notification:)),
+                                                   name: WKExtension.applicationWillEnterForegroundNotification,
+                                                   object: nil)
+        }
+        #endif
     }
 
     /// Compares the last sync date between `NSUbiquitousKeyValueStore` and `UserDefaults`.

Zephyr.podspec

@@ -16,6 +16,7 @@ Pod::Spec.new do |s|
   # Deployment
   s.ios.deployment_target      = '11.0'
   s.tvos.deployment_target     = '11.0'
+  s.watchos.deployment_target  = '9.0'
 
   # Sources
   s.source       = { :git => "https://github.com/ArtSabintsev/Zephyr.git", :tag => s.version.to_s }