Merge pull request #75 from android/mlykotom/ios-viewmodel-scoping

ViewModel Scoping with store in Swift.

The failing CI action is fixed in the following PRs

Author: mlykotom

.github/workflows/Fruitties.yaml

@@ -21,7 +21,7 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Validate Gradle Wrapper
-        uses: gradle/actions/wrapper-validation@v3
+        uses: gradle/wrapper-validation-action@v3
 
       - name: Set up JDK 17
         uses: actions/setup-java@v4

Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/CartScreen.kt

@@ -41,7 +41,6 @@ import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
@@ -51,6 +50,7 @@ import androidx.lifecycle.viewmodel.compose.viewModel
 import com.example.fruitties.android.R
 import com.example.fruitties.android.di.App
 import com.example.fruitties.viewmodel.CartViewModel
+import com.example.fruitties.viewmodel.creationExtras
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -61,13 +61,10 @@ fun CartScreen(onNavBarBack: () -> Unit) {
     // Here we put the KMP-compatible AppContainer into the extras
     // so it can be passed to the ViewModel factory.
     val app = LocalContext.current.applicationContext as App
-    val extras = remember(app) {
-        val container = app.container
-        CartViewModel.creationExtras(container)
-    }
+
     val viewModel: CartViewModel = viewModel(
         factory = CartViewModel.Factory,
-        extras = extras,
+        extras = creationExtras(app.container),
     )
 
     val cartState by viewModel.cartUiState.collectAsState()

Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/ListScreen.kt

@@ -40,7 +40,6 @@ import androidx.compose.material3.TopAppBarColors
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
-import androidx.compose.runtime.remember
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
@@ -53,6 +52,7 @@ import com.example.fruitties.android.R
 import com.example.fruitties.android.di.App
 import com.example.fruitties.model.Fruittie
 import com.example.fruitties.viewmodel.MainViewModel
+import com.example.fruitties.viewmodel.creationExtras
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
@@ -63,13 +63,9 @@ fun ListScreen(onClickViewCart: () -> Unit = {}) {
     // Here we put the KMP-compatible AppContainer into the extras
     // so it can be passed to the ViewModel factory.
     val app = LocalContext.current.applicationContext as App
-    val extras = remember(app) {
-        val container = app.container
-        MainViewModel.creationExtras(container)
-    }
     val viewModel: MainViewModel = viewModel(
         factory = MainViewModel.Factory,
-        extras = extras,
+        extras = creationExtras(app.container),
     )
 
     val uiState by viewModel.homeUiState.collectAsState()

Fruitties/gradle/libs.versions.toml

@@ -34,6 +34,7 @@ skie = "0.10.2"
 sqlite = "2.5.1"
 spotless = "7.0.4"
 okio = "3.12.0"
+kermit = "2.0.4"
 runner = "1.6.2"
 core = "1.6.1"
 junit = "1.2.1"
@@ -74,6 +75,7 @@ androidx-navigation3-runtime = { module = "androidx.navigation3:navigation3-runt
 androidx-navigation3-ui = { module = "androidx.navigation3:navigation3-ui", version.ref = "nav3Core" }
 androidx-lifecycle-viewmodel-navigation3 = { module = "androidx.lifecycle:lifecycle-viewmodel-navigation3", version.ref = "lifecycleViewmodelNav3" }
 kotlinx-serialization-core = { module = "org.jetbrains.kotlinx:kotlinx-serialization-core", version.ref = "kotlinxSerializationCore" }
+kermit = { module = "co.touchlab:kermit", version.ref = "kermit" }
 
 [plugins]
 androidApplication = { id = "com.android.application", version.ref = "agp" }

Fruitties/iosApp/iosApp.xcodeproj/project.pbxproj

@@ -3,15 +3,16 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 54;
+	objectVersion = 70;
 	objects = {
 
 /* Begin PBXBuildFile section */
 		058557BB273AAA24004C7B11 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 058557BA273AAA24004C7B11 /* Assets.xcassets */; };
 		058557D9273AAEEB004C7B11 /* Preview Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 058557D8273AAEEB004C7B11 /* Preview Assets.xcassets */; };
 		2152FB042600AC8F00CF470E /* iOSApp.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2152FB032600AC8F00CF470E /* iOSApp.swift */; };
-		2E8773602BC85C2400BF7C40 /* CartView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2E87735F2BC85C2400BF7C40 /* CartView.swift */; };
-		7555FF83242A565900829871 /* ContentView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7555FF82242A565900829871 /* ContentView.swift */; };
+		2DBC08C52E0C3291000309C8 /* ViewModelStoreOwnerProvider.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2DBC08C42E0C3291000309C8 /* ViewModelStoreOwnerProvider.swift */; };
+		2DBC08C72E0C32CE000309C8 /* ObservableValueWrapper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2DBC08C62E0C32CE000309C8 /* ObservableValueWrapper.swift */; };
+		2DBC08C92E0C96A4000309C8 /* IOSViewModelStoreOwner.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2DBC08C82E0C96A4000309C8 /* IOSViewModelStoreOwner.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -31,12 +32,17 @@
 		058557BA273AAA24004C7B11 /* Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Assets.xcassets; sourceTree = "<group>"; };
 		058557D8273AAEEB004C7B11 /* Preview Assets.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = "Preview Assets.xcassets"; sourceTree = "<group>"; };
 		2152FB032600AC8F00CF470E /* iOSApp.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = iOSApp.swift; sourceTree = "<group>"; };
-		2E87735F2BC85C2400BF7C40 /* CartView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CartView.swift; sourceTree = "<group>"; };
+		2DBC08C42E0C3291000309C8 /* ViewModelStoreOwnerProvider.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewModelStoreOwnerProvider.swift; sourceTree = "<group>"; };
+		2DBC08C62E0C32CE000309C8 /* ObservableValueWrapper.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ObservableValueWrapper.swift; sourceTree = "<group>"; };
+		2DBC08C82E0C96A4000309C8 /* IOSViewModelStoreOwner.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = IOSViewModelStoreOwner.swift; sourceTree = "<group>"; };
 		7555FF7B242A565900829871 /* iosApp.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = iosApp.app; sourceTree = BUILT_PRODUCTS_DIR; };
-		7555FF82242A565900829871 /* ContentView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ContentView.swift; sourceTree = "<group>"; };
 		7555FF8C242A565B00829871 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
+/* Begin PBXFileSystemSynchronizedRootGroup section */
+		2DBC08CA2E0CA0A9000309C8 /* ui */ = {isa = PBXFileSystemSynchronizedRootGroup; explicitFileTypes = {}; explicitFolders = (); path = ui; sourceTree = "<group>"; };
+/* End PBXFileSystemSynchronizedRootGroup section */
+
 /* Begin PBXFrameworksBuildPhase section */
 		7555FF78242A565900829871 /* Frameworks */ = {
 			isa = PBXFrameworksBuildPhase;
@@ -76,12 +82,14 @@
 		7555FF7D242A565900829871 /* iosApp */ = {
 			isa = PBXGroup;
 			children = (
+				2DBC08CA2E0CA0A9000309C8 /* ui */,
 				058557BA273AAA24004C7B11 /* Assets.xcassets */,
-				7555FF82242A565900829871 /* ContentView.swift */,
 				7555FF8C242A565B00829871 /* Info.plist */,
 				2152FB032600AC8F00CF470E /* iOSApp.swift */,
 				058557D7273AAEEB004C7B11 /* Preview Content */,
-				2E87735F2BC85C2400BF7C40 /* CartView.swift */,
+				2DBC08C42E0C3291000309C8 /* ViewModelStoreOwnerProvider.swift */,
+				2DBC08C82E0C96A4000309C8 /* IOSViewModelStoreOwner.swift */,
+				2DBC08C62E0C32CE000309C8 /* ObservableValueWrapper.swift */,
 			);
 			path = iosApp;
 			sourceTree = "<group>";
@@ -110,6 +118,9 @@
 			);
 			dependencies = (
 			);
+			fileSystemSynchronizedGroups = (
+				2DBC08CA2E0CA0A9000309C8 /* ui */,
+			);
 			name = iosApp;
 			productName = iosApp;
 			productReference = 7555FF7B242A565900829871 /* iosApp.app */;
@@ -187,9 +198,10 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				2E8773602BC85C2400BF7C40 /* CartView.swift in Sources */,
 				2152FB042600AC8F00CF470E /* iOSApp.swift in Sources */,
-				7555FF83242A565900829871 /* ContentView.swift in Sources */,
+				2DBC08C92E0C96A4000309C8 /* IOSViewModelStoreOwner.swift in Sources */,
+				2DBC08C72E0C32CE000309C8 /* ObservableValueWrapper.swift in Sources */,
+				2DBC08C52E0C3291000309C8 /* ViewModelStoreOwnerProvider.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Fruitties/iosApp/iosApp/IOSViewModelStoreOwner.swift

@@ -0,0 +1,32 @@
+import SwiftUI
+import shared
+
+/// A ViewModelStoreOwner specifically for iOS.
+/// This is used with from iOS with Kotlin Multiplatform (KMP).
+class IOSViewModelStoreOwner: ObservableObject, SwiftViewModelStoreOwner {
+
+    var viewModelStore: Lifecycle_viewmodelViewModelStore =
+        Lifecycle_viewmodelViewModelStore()
+
+    /// This function allows retrieving the androidx ViewModel from the store.
+    func viewModel<T: Lifecycle_viewmodelViewModel>(
+        key: String? = nil,
+        factory: Lifecycle_viewmodelViewModelProviderFactory,
+        extras: Lifecycle_viewmodelCreationExtras? = nil
+    ) -> T {
+        do {
+            return try viewModelStore.getViewModel(
+                modelClass: T.self,
+                factory: factory,
+                key: key,
+                extras: extras
+            ) as! T
+        } catch {
+            fatalError("Failed to create ViewModel of type \(T.self)")
+        }
+    }
+
+    func clear() {
+        viewModelStore.clear()
+    }
+}

Fruitties/iosApp/iosApp/ObservableValueWrapper.swift

@@ -0,0 +1,17 @@
+import Combine
+import SwiftUI
+import shared
+
+/// A generic wrapper that makes any `Value` type observable by SwiftUI.
+///
+/// Use this to wrap non-`ObservableObject` types when their changes need to update SwiftUI views.
+class ObservableValueWrapper<Value>: ObservableObject {
+
+    /// The wrapped value. Changes trigger SwiftUI view updates.
+    @Published var value: Value
+
+    /// Initializes the wrapper with an initial value.
+    init(value: Value) {
+        self.value = value
+    }
+}

Fruitties/iosApp/iosApp/ViewModelStoreOwnerProvider.swift

@@ -0,0 +1,27 @@
+import SwiftUI
+import shared
+
+/// A SwiftUI `View` that provides a `ViewModelStoreOwner` to its content.
+///
+/// Manages the lifecycle of `ViewModel` instances, scoping them to this view hierarchy.
+/// Clears the associated `ViewModelStore` when the provider disappears.
+struct ViewModelStoreOwnerProvider<Content: View>: View {
+    @StateObject private var viewModelStoreOwner = IOSViewModelStoreOwner()
+    
+    private let content: Content
+
+    /// Initializes the provider with its content, creating a new `IOSViewModelStoreOwner`.
+    init(@ViewBuilder content: () -> Content) {
+        self.content = content()
+    }
+
+    var body: some View {
+        content
+            .environmentObject(viewModelStoreOwner)
+            .onDisappear {
+                viewModelStoreOwner.clear()
+            }
+    }
+}
+
+

Fruitties/iosApp/iosApp/iOSApp.swift

@@ -19,12 +19,23 @@ import shared
 
 @main
 struct iOSApp: App {
-    let appContainer = AppContainer(factory: Factory())
+    /// The application's dependency container, wrapped for SwiftUI observation.
+    let appContainer: ObservableValueWrapper<AppContainer>
+
+    init() {
+        self.appContainer = ObservableValueWrapper<AppContainer>(
+            value: AppContainer(factory: Factory())
+        )
+    }
+
     var body: some Scene {
         WindowGroup {
-            let iosViewModelOwner = IOSViewModelStoreOwner(appContainer: appContainer)
-            ContentView(mainViewModel: iosViewModelOwner.getMainViewModel(),
-                        cartViewModel: iosViewModelOwner.getCartViewModel())
+            /// Provides the root `ViewModelStoreOwner` to the environment, making it accessible to all child views.
+            /// Nested `ViewModelStoreOwnerProvider` instances can create additional, scoped ViewModel stores.
+            ViewModelStoreOwnerProvider {
+                ContentView()
+            }
+            .environmentObject(appContainer)
         }
     }
 }

Fruitties/iosApp/iosApp/CartView.swift renamed to Fruitties/iosApp/iosApp/ui/CartView.swift

@@ -19,13 +19,24 @@ import SwiftUI
 import shared
 
 struct CartView : View {
-    let cartViewModel: CartViewModel
+    /// Injects the `IOSViewModelStoreOwner` from the environment, which manages the lifecycle of `ViewModel` instances.
+    @EnvironmentObject var viewModelStoreOwner: IOSViewModelStoreOwner
 
-    // The ViewModel exposes a StateFlow that we access in SwiftUI with SKIE Observing.
-    // https://skie.touchlab.co/features/flows-in-swiftui
+    /// Injects the `AppContainer` from the environment, providing access to application-wide dependencies.
+    @EnvironmentObject var appContainer: ObservableValueWrapper<AppContainer>
 
     var body: some View {
-        // https://skie.touchlab.co/features/flows-in-swiftui
+        /// Retrieves the `CartViewModel` instance using the `viewModelStoreOwner`.
+        /// The `CartViewModel.Factory` and `creationExtras` are provided to enable dependency injection
+        /// and proper initialization of the ViewModel with its required `AppContainer`.
+        let cartViewModel: CartViewModel = viewModelStoreOwner.viewModel(
+            factory: CartViewModel.companion.Factory,
+            extras: creationExtras(appContainer: appContainer.value)
+        )
+
+        /// Observes the `cartUiState` `StateFlow` from the `CartViewModel` using SKIE's `Observing` utility.
+        /// This allows SwiftUI to react to changes in the cart's UI state.
+        /// For more details, refer to: https://skie.touchlab.co/features/flows-in-swiftui
         Observing(cartViewModel.cartUiState) { cartUIState in
             VStack {
                 HStack {
@@ -44,7 +55,9 @@ struct CartDetailsView: View {
     let cartViewModel: CartViewModel
 
     var body: some View {
-        // https://skie.touchlab.co/features/flows-in-swiftui
+        /// Observes the `cartUiState` `StateFlow` from the `CartViewModel` using SKIE's `Observing` utility.
+        /// This allows SwiftUI to react to changes in the cart's UI state.
+        /// For more details, refer to: https://skie.touchlab.co/features/flows-in-swiftui
         Observing(self.cartViewModel.cartUiState) { cartUIState in
             ScrollView {
                 LazyVStack {