Add .publisher() overload that accepts an array of keys (#148)

Co-authored-by: Sindre Sorhus <[email protected]>

Sources/Defaults/Observation+Combine.swift

@@ -102,7 +102,7 @@ extension Defaults {
  - Warning: This method exists for backwards compatibility and will be deprecated sometime in the future. Use ``Defaults/updates(_:initial:)-9eh8`` instead.
  */
  public static func publisher(
- keys: _AnyKey...,
+ keys: [_AnyKey],
  options: ObservationOptions = [.initial]
  ) -> AnyPublisher<Void, Never> {
  let initial = Empty<Void, Never>(completeImmediately: false).eraseToAnyPublisher()
@@ -118,4 +118,16 @@ extension Defaults {
  combined.merge(with: keyPublisher).eraseToAnyPublisher()
  }
  }
+
+ /**
+ Publisher for multiple `Key<T>` observation, but without specific information about changes.
+
+ - Warning: This method exists for backwards compatibility and will be deprecated sometime in the future. Use ``Defaults/updates(_:initial:)-9eh8`` instead.
+ */
+ public static func publisher(
+ keys: _AnyKey...,
+ options: ObservationOptions = [.initial]
+ ) -> AnyPublisher<Void, Never> {
+ publisher(keys: keys, options: options)
+ }
 }

Sources/Defaults/Observation.swift

@@ -125,6 +125,7 @@ extension Defaults {
  private weak var object: UserDefaults?
  private let key: String
  private let callback: Callback
+ private var isObserving = false
 
  init(object: UserDefaults, key: String, callback: @escaping Callback) {
  self.object = object
@@ -138,10 +139,15 @@ extension Defaults {
 
  func start(options: ObservationOptions) {
  object?.addObserver(self, forKeyPath: key, options: options.toNSKeyValueObservingOptions, context: nil)
+ isObserving = true
  }
 
  func invalidate() {
- object?.removeObserver(self, forKeyPath: key, context: nil)
+ if isObserving {
+ object?.removeObserver(self, forKeyPath: key, context: nil)
+ isObserving = false
+ }
+
  object = nil
  lifetimeAssociation?.cancel()
  }

Tests/DefaultsTests/DefaultsTests.swift

@@ -733,6 +733,23 @@ final class DefaultsTests: XCTestCase {
  waitForExpectations(timeout: 10)
  }
 
+ func testImmediatelyFinishingMultiplePublisherCombine() {
+ let key1 = Defaults.Key<Bool>("observeKey1", default: false)
+ let key2 = Defaults.Key<String>("observeKey2", default: "🦄")
+ let expect = expectation(description: "Observation closure being called without crashing")
+
+ let cancellable = Defaults
+ .publisher(keys: [key1, key2], options: [.initial])
+ .first()
+ .sink { _ in
+ expect.fulfill()
+ }
+
+ cancellable.cancel()
+
+ waitForExpectations(timeout: 10)
+ }
+
  func testKeyEquatable() {
  XCTAssertEqual(Defaults.Key<Bool>("equatableKeyTest", default: false), Defaults.Key<Bool>("equatableKeyTest", default: false))
  }