[CAKER-2] Enable macOS target compatibility (#2)

- adjusted package platform list
- separated AppKit/UIKit specific implementation into `HapticPlayer` component, used by a common service abstraction

Work on xiiagency/Caker#2

Package.swift

@@ -7,6 +7,7 @@ let package =
     platforms: [
       .iOS(.v15),
       .watchOS(.v8),
+      .macOS(.v12),
     ],
     products: [
       .library(

Sources/SwiftUIHaptics/HapticsPlayer+AppKit.swift

@@ -0,0 +1,37 @@
+#if os(macOS)
+
+import SwiftFoundationExtensions
+import os
+
+/**
+ A macOS implementation of the haptics player.
+ 
+ NOTE: Currently a no-op that always returns false for `isAvailable` and does nothing when starting/stopping or playing an event.
+ */
+class HapticsPlayer {
+  private static let logger: Logger = .loggerFor(HapticsPlayer.self)
+  
+  /**
+   NOTE: We currently do not support haptics feedback on macOS.
+   */
+  static let isAvailable: Bool = false
+  
+  /**
+   NOTE: We currently do not support haptics feedback on macOS, this is a no-op.
+   */
+  func start() {}
+  
+  /**
+   NOTE: We currently do not support haptics feedback on macOS, this is a no-op.
+   */
+  func stop() {}
+  
+  /**
+   NOTE: We currently do not support haptics feedback on macOS.
+   */
+  func play(event: HapticEvent) {
+    Self.logger.warning("No haptics support on MacOS.")
+  }
+}
+
+#endif

Sources/SwiftUIHaptics/HapticsPlayer+UIKit.swift

@@ -0,0 +1,139 @@
+#if !os(macOS)
+
+import CoreHaptics
+import SwiftFoundationExtensions
+import SwiftUI
+import os
+
+/**
+ The UIKit implementation of the `HapticsPlayer`, utilizing CoreHaptics.
+ */
+class HapticsPlayer {
+  private static let logger: Logger = .loggerFor(HapticsPlayer.self)
+  
+  /**
+   Returns true if the device supports haptic feedback, false otherwise.
+   */
+  static var isAvailable: Bool {
+    CHHapticEngine.capabilitiesForHardware().supportsHaptics
+  }
+  
+  /**
+   The currently initialized haptics engine.
+   */
+  private var currentEngine: CHHapticEngine? = nil
+  
+  /**
+   Subscribes to foreground/background notifications and initializes the haptics engine.
+   */
+  func start() {
+    startReceivingAppStatusNotifications()
+    setupEngine()
+  }
+  
+  /**
+   Unsubscribes to foreground/background notifications.
+   */
+  func stop() {
+    stopReceivingAppStatusNotifications()
+  }
+  
+  /**
+   Called to subscribe to notifications of the app entering/exiting foreground so that we can start/shutdown the haptics engine to match.
+   */
+  private func startReceivingAppStatusNotifications() {
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(setupEngine),
+      name: UIApplication.willEnterForegroundNotification,
+      object: nil
+    )
+    
+    NotificationCenter.default.addObserver(
+      self,
+      selector: #selector(shutdownEngine),
+      name: UIApplication.willResignActiveNotification,
+      object: nil
+    )
+  }
+  
+  /**
+   Called when de-initialized to unsubscribe from foreground/background notifications.
+   */
+  private func stopReceivingAppStatusNotifications() {
+    NotificationCenter.default.removeObserver(
+      self,
+      name: UIApplication.willEnterForegroundNotification,
+      object: nil
+    )
+    
+    NotificationCenter.default.removeObserver(
+      self,
+      name: UIApplication.willResignActiveNotification,
+      object: nil
+    )
+  }
+  
+  /**
+   Sets up the device's haptic engine. Called when this service is initialized or whenever the app returns to foreground.
+   */
+  @objc
+  private func setupEngine() {
+    shutdownEngine()
+    
+    do {
+      let engine = try CHHapticEngine()
+      engine.start(
+        completionHandler: { [self] error in
+          if let error = error {
+            Self.logger.error("Error starting haptics engine: \(error.description, privacy: .public)")
+            return
+          }
+          
+          currentEngine = engine
+        }
+      )
+    } catch {
+      Self.logger.error("Error creating haptics engine: \(error.description, privacy: .public)")
+    }
+  }
+  
+  /**
+   Shuts down the haptic engine. Called whenever the app enters background.
+   */
+  @objc
+  private func shutdownEngine() {
+    guard let engine = currentEngine else {
+      return
+    }
+    
+    engine.stop(
+      completionHandler: { [self] error in
+        if let error = error {
+          Self.logger.error("Error occurred shutting down haptics engine: \(error.description, privacy: .public)")
+        }
+        
+        currentEngine = nil
+      }
+    )
+  }
+  
+  /**
+   Plays a pattern of haptic events using the current haptics engine, if it is defined and haptics are supported.
+   */
+  func play(event: HapticEvent) {
+    guard let engine = currentEngine else {
+      return
+    }
+    
+    do {
+      let pattern = try CHHapticPattern(events: event.underlyingEvents, parameters: [])
+      let player = try engine.makePlayer(with: pattern)
+      try player.start(atTime: 0)
+    } catch {
+      Self.logger.error("Error attempting to play haptics pattern: \(error.description, privacy: .public)")
+    }
+  }
+}
+
+#endif

Sources/SwiftUIHaptics/HapticsService.swift

@@ -1,24 +1,25 @@
-import CoreHaptics
 import SwiftFoundationExtensions
 import SwiftUI
 import os
 
 /**
  A service that integrates to the device's haptics engine, if it is available.
+ 
+ NOTE: The haptics feedback are only implemented for iOS/watchOS, but not on macOS.
+       The play function will not produce feedback and will return control right away.
  */
 public class HapticsService : ObservableObject {
   private static let logger: Logger = .loggerFor(HapticsService.self)
   
   /**
-   True if the device supports haptic feedback, false otherwise.
+   Return true if the device supports haptic feedback, false otherwise.
    */
-  public private(set) var isAvailable: Bool = CHHapticEngine.capabilitiesForHardware()
-    .supportsHaptics
+  public var isAvailable: Bool {
+    HapticsPlayer.isAvailable
+  }
   
-  /**
-   The currently initialized haptics engine.
-   */
-  private var currentEngine: CHHapticEngine? = nil
+  // The underlying, platform-specific, haptics player.
+  private let player: HapticsPlayer = HapticsPlayer()
   
   public init() {
     initialize()
@@ -29,119 +30,28 @@ public class HapticsService : ObservableObject {
   }
   
   /**
-   Called when the service is initialized, subscribes to foreground/background notifications and initializes the haptics engine.
+   Called when the service is initialized, initializes the `HapticsPlayer` for the current platform.
    
    NOTE: Implemented as a separate fileprivate func in order to allow for the mock of this service to override the initialization process.
    */
   fileprivate func initialize() {
-    startReceivingAppStatusNotifications()
-    setupEngine()
+    player.start()
   }
   
   /**
-   Called when the service is de-initialized, unsubscribes to foreground/background notifications.
+   Called when the service is de-initialized, de-initializes the `HapticsPlayer` for the current platform.
    
    NOTE: Implemented as a separate fileprivate func in order to allow for the mock of this service to override the de-initialization process.
    */
   fileprivate func deinitialize() {
-    stopReceivingAppStatusNotifications()
+    player.stop()
   }
   
   /**
-   Called to subscribe to notifications of the app entering/exiting foreground so that we can start/shutdown the haptics engine to match.
-   */
-  private func startReceivingAppStatusNotifications() {
-    NotificationCenter.default.addObserver(
-      self,
-      selector: #selector(setupEngine),
-      name: UIApplication.willEnterForegroundNotification,
-      object: nil
-    )
-    
-    NotificationCenter.default.addObserver(
-      self,
-      selector: #selector(shutdownEngine),
-      name: UIApplication.willResignActiveNotification,
-      object: nil
-    )
-  }
-  
-  /**
-   Called when de-initialized to unsubscribe from foreground/background notifications.
-   */
-  private func stopReceivingAppStatusNotifications() {
-    NotificationCenter.default.removeObserver(
-      self,
-      name: UIApplication.willEnterForegroundNotification,
-      object: nil
-    )
-    
-    NotificationCenter.default.removeObserver(
-      self,
-      name: UIApplication.willResignActiveNotification,
-      object: nil
-    )
-  }
-  
-  /**
-   Sets up the device's haptic engine. Called when this service is initialized or whenever the app returns to foreground.
-   */
-  @objc
-  private func setupEngine() {
-    shutdownEngine()
-    
-    do {
-      let engine = try CHHapticEngine()
-      engine.start(
-        completionHandler: { [self] error in
-          if let error = error {
-            Self.logger.error("Error starting haptics engine: \(error.description, privacy: .public)")
-            return
-          }
-          
-          currentEngine = engine
-        }
-      )
-    } catch {
-      Self.logger.error("Error creating haptics engine: \(error.description, privacy: .public)")
-    }
-  }
-  
-  /**
-   Shuts down the haptic engine. Called whenever the app enters background.
-   */
-  @objc
-  private func shutdownEngine() {
-    guard let engine = currentEngine else {
-      return
-    }
-    
-    engine.stop(
-      completionHandler: { [self] error in
-        if let error = error {
-          Self.logger.error("Error occurred shutting down haptics engine: \(error.description, privacy: .public)")
-        }
-        
-        currentEngine = nil
-      }
-    )
-  }
-  
-  /**
-   Plays a pattern of haptic events using the current haptics engine, if it is defined and haptics are supported.
+   Plays a pattern of haptic events using the current haptics player, if haptics are supported.
    */
   public func play(event: HapticEvent) {
-    guard let engine = currentEngine else {
-      return
-    }
-    
-    do {
-      let pattern = try CHHapticPattern(events: event.underlyingEvents, parameters: [])
-      let player = try engine.makePlayer(with: pattern)
-      try player.start(atTime: 0)
-    } catch {
-      Self.logger.error("Error attempting to play haptics pattern: \(error.description, privacy: .public)")
-    }
+    player.play(event: event)
   }
 }