Custom UserDefaults suite

Sources/KeyboardShortcuts/KeyboardShortcuts.swift

@@ -37,6 +37,25 @@ public enum KeyboardShortcuts {
 
 	private static var openMenuObserver: NSObjectProtocol?
 	private static var closeMenuObserver: NSObjectProtocol?
+	private static var userDefaultsObservers = [UserDefaultsObservation]()
+
+	public static var customDefaults: UserDefaults? {
+		get {
+			_customDefaults
+		}
+
+		set {
+			_customDefaults = newValue
+		}
+	}
+
+	static var _customDefaults: UserDefaults? {
+		didSet {
+			userDefaults = _customDefaults ?? .standard
+		}
+	}
+
+	static var userDefaults: UserDefaults = .standard
 
 	/**
 	When `true`, event handlers will not be called for registered keyboard shortcuts.
@@ -59,7 +78,7 @@ public enum KeyboardShortcuts {
 	}
 
 	static var allNames: Set<Name> {
-		UserDefaults.standard.dictionaryRepresentation()
+		KeyboardShortcuts.userDefaults.dictionaryRepresentation()
 			.compactMap { key, _ in
 				guard key.hasPrefix(userDefaultsPrefix) else {
 					return nil
@@ -326,7 +345,7 @@ public enum KeyboardShortcuts {
 	*/
 	public static func getShortcut(for name: Name) -> Shortcut? {
 		guard
-			let data = UserDefaults.standard.string(forKey: userDefaultsKey(for: name))?.data(using: .utf8),
+			let data = KeyboardShortcuts.userDefaults.string(forKey: userDefaultsKey(for: name))?.data(using: .utf8),
 			let decoded = try? JSONDecoder().decode(Shortcut.self, from: data)
 		else {
 			return nil
@@ -410,6 +429,7 @@ public enum KeyboardShortcuts {
 	*/
 	public static func onKeyDown(for name: Name, action: @escaping () -> Void) {
 		legacyKeyDownHandlers[name, default: []].append(action)
+		startObservingShortcut(for: name)
 		registerShortcutIfNeeded(for: name)
 	}
 
@@ -436,14 +456,40 @@ public enum KeyboardShortcuts {
 	*/
 	public static func onKeyUp(for name: Name, action: @escaping () -> Void) {
 		legacyKeyUpHandlers[name, default: []].append(action)
+		startObservingShortcut(for: name)
 		registerShortcutIfNeeded(for: name)
 	}
 
 	private static let userDefaultsPrefix = "KeyboardShortcuts_"
 
-	private static func userDefaultsKey(for shortcutName: Name) -> String { "\(userDefaultsPrefix)\(shortcutName.rawValue)"
+	private static func userDefaultsKey(for shortcutName: Name) -> String { 
+		"\(userDefaultsPrefix)\(shortcutName.rawValue)"
 	}
-
+
+	/**
+	Start observing UserDefaults changes for a specific shortcut name.
+	Only starts observation if the shortcut is not already being observed.
+	*/
+	private static func startObservingShortcut(for name: Name) {
+		let key = userDefaultsKey(for: name)
+
+		let observation = UserDefaultsObservation(
+			suite: userDefaults,
+			name: name,
+			key: key
+		) { name, value in
+			if value == nil {
+				self.unregisterShortcutIfNeeded(for: name)
+			} else {
+				self.registerShortcutIfNeeded(for: name)
+			}
+		}
+
+		observation.start()
+
+		userDefaultsObservers.append(observation)
+	}
+
 	static func userDefaultsDidChange(name: Name) {
 		// TODO: Use proper UserDefaults observation instead of this.
 		NotificationCenter.default.post(name: .shortcutByNameDidChange, object: nil, userInfo: ["name": name])
@@ -459,7 +505,7 @@ public enum KeyboardShortcuts {
 		}
 
 		register(shortcut)
-		UserDefaults.standard.set(encoded, forKey: userDefaultsKey(for: name))
+		KeyboardShortcuts.userDefaults.set(encoded, forKey: userDefaultsKey(for: name))
 		userDefaultsDidChange(name: name)
 	}
 
@@ -468,7 +514,7 @@ public enum KeyboardShortcuts {
 			return
 		}
 
-		UserDefaults.standard.set(false, forKey: userDefaultsKey(for: name))
+		KeyboardShortcuts.userDefaults.set(false, forKey: userDefaultsKey(for: name))
 		unregister(shortcut)
 		userDefaultsDidChange(name: name)
 	}
@@ -478,13 +524,13 @@ public enum KeyboardShortcuts {
 			return
 		}
 
-		UserDefaults.standard.removeObject(forKey: userDefaultsKey(for: name))
+		KeyboardShortcuts.userDefaults.removeObject(forKey: userDefaultsKey(for: name))
 		unregister(shortcut)
 		userDefaultsDidChange(name: name)
 	}
 
 	static func userDefaultsContains(name: Name) -> Bool {
-		UserDefaults.standard.object(forKey: userDefaultsKey(for: name)) != nil
+		KeyboardShortcuts.userDefaults.object(forKey: userDefaultsKey(for: name)) != nil
 	}
 }
 

Sources/KeyboardShortcuts/Utilities.swift

@@ -559,3 +559,104 @@
 		self = Character(content)
 	}
 }
+
+final class UserDefaultsObservation: NSObject {
+	typealias Callback = (_ name: KeyboardShortcuts.Name, _ newKeyValue: String?) -> Void
+
+	private let name: KeyboardShortcuts.Name
+	private let key: String
+	static var observationContext = 0
+	private weak var suite: UserDefaults?
+	private var isObserving = false
+	private let callback: Callback
+	private var lock = NSLock()
+
+	init(
+		suite: UserDefaults,
+		name: KeyboardShortcuts.Name,
+		key: String,
+		_ callback: @escaping Callback
+	) {
+		self.suite = suite
+		self.name = name
+		self.key = key
+		self.callback = callback
+	}
+
+	deinit {
+		invalidate()
+	}
+
+	func start() {
+		lock.lock()
+
+		guard !isObserving else {
+			return
+		}
+
+		suite?.addObserver(
+			self,
+			forKeyPath: key,
+			options: [.new],
+			context: &Self.observationContext
+		)
+		isObserving = true
+
+		lock.unlock()
+	}
+
+	func invalidate() {
+		lock.lock()
+
+		guard isObserving else {
+			return
+		}
+
+		suite?.removeObserver(
+			self,
+			forKeyPath: key
+		)
+		isObserving = false
+		suite = nil
+
+		lock.unlock()
+	}
+
+	override func observeValue(
+		forKeyPath keyPath: String?,
+		of object: Any?,
+		change: [NSKeyValueChangeKey : Any]?,
+		context: UnsafeMutableRawPointer?
+	) {
+		guard
+			context == &Self.observationContext
+		else {
+			super.observeValue(
+				forKeyPath: keyPath,
+				of: object,
+				change: change,
+				context: context
+			)
+			return
+		}
+
+		guard let selfSuite = suite else {
+			invalidate()
+			return
+		}
+
+		guard
+			selfSuite == (object as? UserDefaults),
+			let change
+		else {
+			return
+		}
+
+		guard keyPath == key else {
+			return
+		}
+
+		let encodedString = change[.newKey] as? String
+		callback(self.name, encodedString)
+	}
+}