akexorcist · March 12, 2025 06:40 · Mar 12, 2025
diff --git a/ComposableScopeViewModelProvider.kt b/ComposableScopeViewModelProvider.kt
@@ -0,0 +1,34 @@
+@SuppressLint("RestrictedApi")
+@Composable
+fun <T : ViewModel> ComposableScopeViewModelProvider(
+    key: String,
+    viewModelFactory: @Composable (key: String) -> T,
+    content: @Composable (viewModel: T) -> Unit,
+) {
+    val activity = LocalActivity.current ?: return
+    val viewModelStoreOwner = LocalViewModelStoreOwner.current ?: return
+    val lifecycleOwner = LocalLifecycleOwner.current
+
+    DisposableEffect(lifecycleOwner) {
+        var isConfigurationChanging = false
+        val observer = LifecycleEventObserver { _, event ->
+            if (event == Lifecycle.Event.ON_DESTROY) {
+                isConfigurationChanging = activity.isChangingConfigurations
+            }
+        }
+        lifecycleOwner.lifecycle.addObserver(observer)
+        onDispose {
+            lifecycleOwner.lifecycle.removeObserver(observer)
+            if (!isConfigurationChanging) {
+                // Replace the ViewModel with an empty one to make the ViewModel clear
+                viewModelStoreOwner.viewModelStore.put(
+                    key = key,
+                    viewModel = object : ViewModel() {
+                        override fun onCleared() = Unit
+                    }
+                )
+            }
+        }
+    }
+    content(viewModelFactory(key))
+}
diff --git a/NoSavedStateViewModel.kt b/NoSavedStateViewModel.kt
@@ -0,0 +1,48 @@
+/*
+ * Composable has gone by UI logic: ViewModel and data are cleared
+ * Configuration changes:           ViewModel and data still exist.
+ * Application process recreation:  Clear ViewModel and data.
+ */
+
+// SectionViewModel.kt
+class SectionViewModel(private val savedStateHandle: SavedStateHandle) : ViewModel() {
+    val uiState: StateFlow<String?> =
+        savedStateHandle.getStateFlow<String?>(
+            key = "uiState",
+            initialValue = null,
+        )
+
+    fun updateValue() {
+        val newValue = UUID.randomUUID().toString()
+        savedStateHandle["uiState"] = newValue
+    }
+
+    override fun onCleared() {
+        super.onCleared()
+        // Clean up is requires for any saved state value
+        savedStateHandle.keys().forEach { key ->
+            savedStateHandle.remove<Any>(key)
+        }
+    }
+}
+
+// SampleScreen.kt
+@Composable
+fun SampleScreen() {
+  var showSection by remember { mutableStateOf<Boolean>(false)
+
+  /* ... */
+  if (showSection) {
+    ComposableScopeViewModelProvider(
+      key = "section",
+      factory = { key -> viewModel<SectionViewModel>(key = key) }
+      // Koin library
+      // factory = { key -> koinViewModel<SectionViewModel>(key = key) },
+    ) { viewModel ->
+      StatefulSection()
+    }
+  }
+}
+
+@Composable
+fun StatefulSection(viewModel: SectionViewModel) { /* .. */ }
diff --git a/WithSavedStateViewModel.kt b/WithSavedStateViewModel.kt
@@ -0,0 +1,37 @@
+/*
+ * Composable has gone by UI logic: ViewModel and data are cleared.
+ * Configuration changes:           ViewModel and data still exist.
+ * Application process recreation:  ViewModel cleared, but data still exists.
+ */
+
+// SectionViewModel.kt
+class SectionViewModel(private val savedStateHandle: SavedStateHandle) : ViewModel() {
+   private val _uiState = MutableStateFlow<String?>(null)
+   val uiState: StateFlow<String?> = _uiState
+
+    fun updateValue() {
+        val newValue = UUID.randomUUID().toString()
+       _uiState2.update { newValue }
+    }
+}
+
+// SampleScreen.kt
+@Composable
+fun SampleScreen() {
+  var showSection by remember { mutableStateOf<Boolean>(false)
+
+  /* ... */
+  if (showSection) {
+    ComposableScopeViewModelProvider(
+      key = "section",
+      factory = { key -> viewModel<SectionViewModel>(key = key) }
+      // Koin library
+      // factory = { key -> koinViewModel<SectionViewModel>(key = key) },
+    ) { viewModel ->
+      StatefulSection()
+    }
+  }
+}
+
+@Composable
+fun StatefulSection(viewModel: SectionViewModel) { /* .. */ }