Compose Multiplatform Patterns

affaan-m/ECC/pi/core/skills/compose-multiplatform-patterns

by affaan-mef648e01899ba3e8dc6371642deaaf64b4477775No license275K starsListed Oct 9, 2026Updated Oct 9, 2026Repository updated 4 days ago

Compose Multiplatform and Jetpack Compose patterns for KMP projects — state management, navigation, theming, performance, and platform-specific UI. Use when building Compose or Jetpack Compose UI, state, navigation, or theming in a KMP project.

Instructions onlySoftware Development

AI-generated overview

Reference patterns for building Compose Multiplatform and Jetpack Compose UI in KMP projects.

What it does: Provides guidance and code patterns for shared UI across Android, iOS, Desktop, and Web using Compose Multiplatform and Jetpack Compose. It covers state management with ViewModels and StateFlow, type-safe navigation, composable design, platform-specific expect/actual UI, performance tuning, and Material 3 theming. It also lists anti-patterns to avoid. It produces instructions and code examples, not files or scripts.
When to use it: Use it when building or reviewing Compose or Jetpack Compose UI in a Kotlin Multiplatform project. It fits work on UI state, navigation, reusable composables, theming, or recomposition performance.
Requirements: No scripts or tooling are shipped; it is instructions only. Applying the examples assumes a Kotlin Multiplatform or Android project with Compose, Compose Navigation, and related libraries such as Koin and Material 3.

Compose Multiplatform Patterns

Patterns for building shared UI across Android, iOS, Desktop, and Web using Compose Multiplatform and Jetpack Compose. Covers state management, navigation, theming, and performance.

When to Activate

Building Compose UI (Jetpack Compose or Compose Multiplatform)
Managing UI state with ViewModels and Compose state
Implementing navigation in KMP or Android projects
Designing reusable composables and design systems
Optimizing recomposition and rendering performance

State Management

ViewModel + Single State Object

Use a single data class for screen state. Expose it as StateFlow and collect in Compose:

kotlin

data class ItemListState(    val items: List<Item> = emptyList(),    val isLoading: Boolean = false,    val error: String? = null,    val searchQuery: String = "")
class ItemListViewModel(    private val getItems: GetItemsUseCase) : ViewModel() {    private val _state = MutableStateFlow(ItemListState())    val state: StateFlow<ItemListState> = _state.asStateFlow()
    fun onSearch(query: String) {        _state.update { it.copy(searchQuery = query) }        loadItems(query)    }
    private fun loadItems(query: String) {        viewModelScope.launch {            _state.update { it.copy(isLoading = true) }            getItems(query).fold(                onSuccess = { items -> _state.update { it.copy(items = items, isLoading = false) } },                onFailure = { e -> _state.update { it.copy(error = e.message, isLoading = false) } }            )        }    }}

data class ItemListState(    val items: List<Item> = emptyList(),    val isLoading: Boolean = false,    val error: String? = null,    val searchQuery: String = "")
class ItemListViewModel(    private val getItems: GetItemsUseCase) : ViewModel() {    private val _state = MutableStateFlow(ItemListState())    val state: StateFlow<ItemListState> = _state.asStateFlow()
    fun onSearch(query: String) {        _state.update { it.copy(searchQuery = query) }        loadItems(query)    }
    private fun loadItems(query: String) {        viewModelScope.launch {            _state.update { it.copy(isLoading = true) }            getItems(query).fold(                onSuccess = { items -> _state.update { it.copy(items = items, isLoading = false) } },                onFailure = { e -> _state.update { it.copy(error = e.message, isLoading = false) } }            )        }    }}

Collecting State in Compose

kotlin

@Composablefun ItemListScreen(viewModel: ItemListViewModel = koinViewModel()) {    val state by viewModel.state.collectAsStateWithLifecycle()
    ItemListContent(        state = state,        onSearch = viewModel::onSearch    )}
@Composableprivate fun ItemListContent(    state: ItemListState,    onSearch: (String) -> Unit) {    // Stateless composable — easy to preview and test}

@Composablefun ItemListScreen(viewModel: ItemListViewModel = koinViewModel()) {    val state by viewModel.state.collectAsStateWithLifecycle()
    ItemListContent(        state = state,        onSearch = viewModel::onSearch    )}
@Composableprivate fun ItemListContent(    state: ItemListState,    onSearch: (String) -> Unit) {    // Stateless composable — easy to preview and test}

Event Sink Pattern

For complex screens, use a sealed interface for events instead of multiple callback lambdas:

kotlin

sealed interface ItemListEvent {    data class Search(val query: String) : ItemListEvent    data class Delete(val itemId: String) : ItemListEvent    data object Refresh : ItemListEvent}
// In ViewModelfun onEvent(event: ItemListEvent) {    when (event) {        is ItemListEvent.Search -> onSearch(event.query)        is ItemListEvent.Delete -> deleteItem(event.itemId)        is ItemListEvent.Refresh -> loadItems(_state.value.searchQuery)    }}
// In Composable — single lambda instead of manyItemListContent(    state = state,    onEvent = viewModel::onEvent)

sealed interface ItemListEvent {    data class Search(val query: String) : ItemListEvent    data class Delete(val itemId: String) : ItemListEvent    data object Refresh : ItemListEvent}
// In ViewModelfun onEvent(event: ItemListEvent) {    when (event) {        is ItemListEvent.Search -> onSearch(event.query)        is ItemListEvent.Delete -> deleteItem(event.itemId)        is ItemListEvent.Refresh -> loadItems(_state.value.searchQuery)    }}
// In Composable — single lambda instead of manyItemListContent(    state = state,    onEvent = viewModel::onEvent)

Navigation

Type-Safe Navigation (Compose Navigation 2.8+)

Define routes as @Serializable objects:

kotlin

@Serializable data object HomeRoute@Serializable data class DetailRoute(val id: String)@Serializable data object SettingsRoute
@Composablefun AppNavHost(navController: NavHostController = rememberNavController()) {    NavHost(navController, startDestination = HomeRoute) {        composable<HomeRoute> {            HomeScreen(onNavigateToDetail = { id -> navController.navigate(DetailRoute(id)) })        }        composable<DetailRoute> { backStackEntry ->            val route = backStackEntry.toRoute<DetailRoute>()            DetailScreen(id = route.id)        }        composable<SettingsRoute> { SettingsScreen() }    }}

@Serializable data object HomeRoute@Serializable data class DetailRoute(val id: String)@Serializable data object SettingsRoute
@Composablefun AppNavHost(navController: NavHostController = rememberNavController()) {    NavHost(navController, startDestination = HomeRoute) {        composable<HomeRoute> {            HomeScreen(onNavigateToDetail = { id -> navController.navigate(DetailRoute(id)) })        }        composable<DetailRoute> { backStackEntry ->            val route = backStackEntry.toRoute<DetailRoute>()            DetailScreen(id = route.id)        }        composable<SettingsRoute> { SettingsScreen() }    }}

Dialog and Bottom Sheet Navigation

Use dialog() and overlay patterns instead of imperative show/hide:

kotlin

NavHost(navController, startDestination = HomeRoute) {    composable<HomeRoute> { /* ... */ }    dialog<ConfirmDeleteRoute> { backStackEntry ->        val route = backStackEntry.toRoute<ConfirmDeleteRoute>()        ConfirmDeleteDialog(            itemId = route.itemId,            onConfirm = { navController.popBackStack() },            onDismiss = { navController.popBackStack() }        )    }}

NavHost(navController, startDestination = HomeRoute) {    composable<HomeRoute> { /* ... */ }    dialog<ConfirmDeleteRoute> { backStackEntry ->        val route = backStackEntry.toRoute<ConfirmDeleteRoute>()        ConfirmDeleteDialog(            itemId = route.itemId,            onConfirm = { navController.popBackStack() },            onDismiss = { navController.popBackStack() }        )    }}

Composable Design

Slot-Based APIs

Design composables with slot parameters for flexibility:

kotlin

@Composablefun AppCard(    modifier: Modifier = Modifier,    header: @Composable () -> Unit = {},    content: @Composable ColumnScope.() -> Unit,    actions: @Composable RowScope.() -> Unit = {}) {    Card(modifier = modifier) {        Column {            header()            Column(content = content)            Row(horizontalArrangement = Arrangement.End, content = actions)        }    }}

@Composablefun AppCard(    modifier: Modifier = Modifier,    header: @Composable () -> Unit = {},    content: @Composable ColumnScope.() -> Unit,    actions: @Composable RowScope.() -> Unit = {}) {    Card(modifier = modifier) {        Column {            header()            Column(content = content)            Row(horizontalArrangement = Arrangement.End, content = actions)        }    }}

Modifier Ordering

Modifier order matters — apply in this sequence:

kotlin

Text(    text = "Hello",    modifier = Modifier        .padding(16.dp)          // 1. Layout (padding, size)        .clip(RoundedCornerShape(8.dp))  // 2. Shape        .background(Color.White) // 3. Drawing (background, border)        .clickable { }           // 4. Interaction)

Text(    text = "Hello",    modifier = Modifier        .padding(16.dp)          // 1. Layout (padding, size)        .clip(RoundedCornerShape(8.dp))  // 2. Shape        .background(Color.White) // 3. Drawing (background, border)        .clickable { }           // 4. Interaction)

KMP Platform-Specific UI

expect/actual for Platform Composables

kotlin

// commonMain@Composableexpect fun PlatformStatusBar(darkIcons: Boolean)
// androidMain@Composableactual fun PlatformStatusBar(darkIcons: Boolean) {    val systemUiController = rememberSystemUiController()    SideEffect { systemUiController.setStatusBarColor(Color.Transparent, darkIcons) }}
// iosMain@Composableactual fun PlatformStatusBar(darkIcons: Boolean) {    // iOS handles this via UIKit interop or Info.plist}

// commonMain@Composableexpect fun PlatformStatusBar(darkIcons: Boolean)
// androidMain@Composableactual fun PlatformStatusBar(darkIcons: Boolean) {    val systemUiController = rememberSystemUiController()    SideEffect { systemUiController.setStatusBarColor(Color.Transparent, darkIcons) }}
// iosMain@Composableactual fun PlatformStatusBar(darkIcons: Boolean) {    // iOS handles this via UIKit interop or Info.plist}

Performance

Stable Types for Skippable Recomposition

Mark classes as @Stable or @Immutable when all properties are stable:

kotlin

@Immutabledata class ItemUiModel(    val id: String,    val title: String,    val description: String,    val progress: Float)

@Immutabledata class ItemUiModel(    val id: String,    val title: String,    val description: String,    val progress: Float)

Use `key()` and Lazy Lists Correctly

kotlin

LazyColumn {    items(        items = items,        key = { it.id }  // Stable keys enable item reuse and animations    ) { item ->        ItemRow(item = item)    }}

LazyColumn {    items(        items = items,        key = { it.id }  // Stable keys enable item reuse and animations    ) { item ->        ItemRow(item = item)    }}

Defer Reads with `derivedStateOf`

kotlin

val listState = rememberLazyListState()val showScrollToTop by remember {    derivedStateOf { listState.firstVisibleItemIndex > 5 }}

val listState = rememberLazyListState()val showScrollToTop by remember {    derivedStateOf { listState.firstVisibleItemIndex > 5 }}

Avoid Allocations in Recomposition

kotlin

// BAD — new lambda and list every recompositionitems.filter { it.isActive }.forEach { ActiveItem(it, onClick = { handle(it) }) }
// GOOD — key each item so callbacks stay attached to the right rowval activeItems = remember(items) { items.filter { it.isActive } }activeItems.forEach { item ->    key(item.id) {        ActiveItem(item, onClick = { handle(item) })    }}

// BAD — new lambda and list every recompositionitems.filter { it.isActive }.forEach { ActiveItem(it, onClick = { handle(it) }) }
// GOOD — key each item so callbacks stay attached to the right rowval activeItems = remember(items) { items.filter { it.isActive } }activeItems.forEach { item ->    key(item.id) {        ActiveItem(item, onClick = { handle(item) })    }}

Theming

Material 3 Dynamic Theming

kotlin

@Composablefun AppTheme(    darkTheme: Boolean = isSystemInDarkTheme(),    dynamicColor: Boolean = true,    content: @Composable () -> Unit) {    val colorScheme = when {        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {            if (darkTheme) dynamicDarkColorScheme(LocalContext.current)            else dynamicLightColorScheme(LocalContext.current)        }        darkTheme -> darkColorScheme()        else -> lightColorScheme()    }
    MaterialTheme(colorScheme = colorScheme, content = content)}

@Composablefun AppTheme(    darkTheme: Boolean = isSystemInDarkTheme(),    dynamicColor: Boolean = true,    content: @Composable () -> Unit) {    val colorScheme = when {        dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {            if (darkTheme) dynamicDarkColorScheme(LocalContext.current)            else dynamicLightColorScheme(LocalContext.current)        }        darkTheme -> darkColorScheme()        else -> lightColorScheme()    }
    MaterialTheme(colorScheme = colorScheme, content = content)}

Anti-Patterns to Avoid

Using mutableStateOf in ViewModels when MutableStateFlow with collectAsStateWithLifecycle is safer for lifecycle
Passing NavController deep into composables — pass lambda callbacks instead
Heavy computation inside @Composable functions — move to ViewModel or remember {}
Using LaunchedEffect(Unit) as a substitute for ViewModel init — it re-runs on configuration change in some setups
Creating new object instances in composable parameters — causes unnecessary recomposition

References

See skill: android-clean-architecture for module structure and layering. See skill: kotlin-coroutines-flows for coroutine and Flow patterns.

Source and attribution

Source:affaan-m/ECCinpi/core/skills/compose-multiplatform-patternsat commitef648e0

License: No license

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Compose Multiplatform Patterns

Compose Multiplatform Patterns

When to Activate

State Management

ViewModel + Single State Object

Collecting State in Compose

Event Sink Pattern

Navigation

Type-Safe Navigation (Compose Navigation 2.8+)

Dialog and Bottom Sheet Navigation

Composable Design

Slot-Based APIs

Modifier Ordering

KMP Platform-Specific UI

expect/actual for Platform Composables

Performance

Stable Types for Skippable Recomposition

Use `key()` and Lazy Lists Correctly

Defer Reads with `derivedStateOf`

Avoid Allocations in Recomposition

Theming

Material 3 Dynamic Theming

Anti-Patterns to Avoid

References

Source and attribution

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Compose Multiplatform Patterns

Compose Multiplatform Patterns

When to Activate

State Management

ViewModel + Single State Object

Collecting State in Compose

Event Sink Pattern

Navigation

Type-Safe Navigation (Compose Navigation 2.8+)

Dialog and Bottom Sheet Navigation

Composable Design

Slot-Based APIs

Modifier Ordering

KMP Platform-Specific UI

expect/actual for Platform Composables

Performance

Stable Types for Skippable Recomposition

Use key() and Lazy Lists Correctly

Defer Reads with derivedStateOf

Avoid Allocations in Recomposition

Theming

Material 3 Dynamic Theming

Anti-Patterns to Avoid

References

Source and attribution

More from affaan-m/ECC

Unified Notifications Ops

Verification Loop

Ui To Vue

Unified Memory

Visa Doc Translate

Team Builder

More in Software Development

Playground

M5 Onboard

Cardputer Buddy

Web Design Guidelines

Vercel React Native Skills

Vercel React Best Practices

Use `key()` and Lazy Lists Correctly

Defer Reads with `derivedStateOf`