refactor: Map app example

Examples/Packages/iOS/Sources/ExampleMap/Atoms.swift

@@ -1,42 +1,28 @@
 import Atoms
 import CoreLocation
 
-struct LocationManagerAtom: ValueAtom, Hashable {
-    func value(context: Context) -> LocationManagerProtocol {
-        let manager = CLLocationManager()
-        let delegate = LocationManagerDelegate()
-
-        manager.delegate = delegate
-        manager.desiredAccuracy = kCLLocationAccuracyBest
-        context.addTermination(manager.stopUpdatingLocation)
-        context.keepUntilTermination(delegate)
-        delegate.onChange = {
-            context.reset(AuthorizationStatusAtom())
-        }
+final class LocationObserver: NSObject, ObservableObject, CLLocationManagerDelegate {
+    let manager: LocationManagerProtocol
 
-        return manager
+    deinit {
+        manager.stopUpdatingLocation()
     }
-}
 
-struct CoordinateAtom: ValueAtom, Hashable {
-    func value(context: Context) -> CLLocationCoordinate2D? {
-        let manager = context.watch(LocationManagerAtom())
-        return manager.location?.coordinate
+    init(manager: LocationManagerProtocol) {
+        self.manager = manager
+        super.init()
+        manager.delegate = self
     }
-}
 
-struct AuthorizationStatusAtom: ValueAtom, Hashable {
-    func value(context: Context) -> CLAuthorizationStatus {
-        let manager = context.watch(LocationManagerAtom())
-        return manager.authorizationStatus
-    }
-}
+    convenience override init() {
+        let manager = CLLocationManager()
+        manager.desiredAccuracy = kCLLocationAccuracyBest
 
-private final class LocationManagerDelegate: NSObject, CLLocationManagerDelegate {
-    var onChange: (() -> Void)?
+        self.init(manager: manager)
+    }
 
     func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
-        onChange?()
+        objectWillChange.send()
 
         switch manager.authorizationStatus {
         case .authorizedAlways, .authorizedWhenInUse:
@@ -57,3 +43,22 @@ private final class LocationManagerDelegate: NSObject, CLLocationManagerDelegate
         print(error.localizedDescription)
     }
 }
+
+struct LocationObserverAtom: ObservableObjectAtom, Hashable {
+    func object(context: Context) -> LocationObserver {
+        LocationObserver()
+    }
+}
+
+struct CoordinateAtom: ValueAtom, Hashable {
+    func value(context: Context) -> CLLocationCoordinate2D? {
+        let observer = context.watch(LocationObserverAtom())
+        return observer.manager.location?.coordinate
+    }
+}
+
+struct AuthorizationStatusAtom: ValueAtom, Hashable {
+    func value(context: Context) -> CLAuthorizationStatus {
+        context.watch(LocationObserverAtom().select(\.manager.authorizationStatus))
+    }
+}

Examples/Packages/iOS/Sources/ExampleMap/Dependency/LocationManager.swift

@@ -1,10 +1,12 @@
 import CoreLocation
 
-protocol LocationManagerProtocol {
+protocol LocationManagerProtocol: AnyObject {
     var delegate: CLLocationManagerDelegate? { get set }
     var desiredAccuracy: CLLocationAccuracy { get set }
     var location: CLLocation? { get }
     var authorizationStatus: CLAuthorizationStatus { get }
+
+    func stopUpdatingLocation()
 }
 
 extension CLLocationManager: LocationManagerProtocol {}
@@ -14,4 +16,9 @@ final class MockLocationManager: LocationManagerProtocol {
     var desiredAccuracy = kCLLocationAccuracyKilometer
     var location: CLLocation? = nil
     var authorizationStatus = CLAuthorizationStatus.notDetermined
+    var isUpdatingLocation = true
+
+    func stopUpdatingLocation() {
+        isUpdatingLocation = false
+    }
 }

Examples/Packages/iOS/Tests/ExampleMapTests/ExampleMapTests.swift

@@ -6,28 +6,68 @@ import XCTest
 
 @MainActor
 final class ExampleMapTests: XCTestCase {
+    func testLocationObserverAtom() {
+        let atom = LocationObserverAtom()
+        let context = AtomTestContext()
+        let manager = MockLocationManager()
+
+        context.override(atom) { _ in
+            LocationObserver(manager: manager)
+        }
+
+        context.watch(atom)
+
+        XCTAssertNotNil(manager.delegate)
+        XCTAssertTrue(manager.isUpdatingLocation)
+
+        context.unwatch(atom)
+
+        XCTAssertFalse(manager.isUpdatingLocation)
+    }
+
     func testCoordinateAtom() {
         let atom = CoordinateAtom()
         let context = AtomTestContext()
-        let locationManager = MockLocationManager()
+        let manager = MockLocationManager()
 
-        context.override(LocationManagerAtom()) { _ in locationManager }
+        context.override(LocationObserverAtom()) { _ in
+            LocationObserver(manager: manager)
+        }
 
-        locationManager.location = CLLocation(latitude: 1, longitude: 2)
+        manager.location = CLLocation(latitude: 1, longitude: 2)
 
         XCTAssertEqual(context.watch(atom)?.latitude, 1)
         XCTAssertEqual(context.watch(atom)?.longitude, 2)
     }
 
-    func testAuthorizationStatusAtom() {
+    func testAuthorizationStatusAtom() async {
         let atom = AuthorizationStatusAtom()
-        let locationManager = MockLocationManager()
+        let manager = MockLocationManager()
         let context = AtomTestContext()
+        let observer = LocationObserver(manager: manager)
 
-        context.override(LocationManagerAtom()) { _ in locationManager }
+        context.override(LocationObserverAtom()) { _ in
+            observer
+        }
 
-        locationManager.authorizationStatus = .authorizedWhenInUse
+        manager.authorizationStatus = .authorizedWhenInUse
 
         XCTAssertEqual(context.watch(atom), .authorizedWhenInUse)
+
+        manager.authorizationStatus = .authorizedAlways
+
+        Task {
+            observer.objectWillChange.send()
+        }
+
+        await context.waitUntilNextUpdate()
+
+        XCTAssertEqual(context.watch(atom), .authorizedAlways)
+
+        observer.objectWillChange.send()
+        let didUpdate = await context.waitUntilNextUpdate(timeout: 1)
+
+        // Should not update if authorizationStatus is not changed.
+        XCTAssertFalse(didUpdate)
     }
 }