start building kmp app with material design 3 expressive 2024
Are you ready to revolutionize your mobile development workflow? Building Kotlin Multiplatform (KMP) apps with Material Design 3 Expressive isn’t just a trend—it’s the future of efficient, beautiful cross-platform development. As an Android developer working with Kotlin, you’re perfectly positioned to leverage this powerful combination that delivers native performance with stunning, adaptive UIs across multiple platforms.
Material Design 3 represents Google’s most sophisticated design system yet, introducing expressive components, dynamic theming, and emotionally intelligent interfaces. When paired with KMP’s code-sharing capabilities, you can create applications that not only look exceptional but also maintain consistency across Android, iOS, and beyond while dramatically reducing development time.
The mobile development landscape has shifted dramatically in 2024. Users expect seamless experiences across devices, while businesses demand faster delivery cycles and reduced development costs. Material Design 3 addresses these challenges by providing:
Successful KMP apps with Material Design 3 follow specific architectural and design principles that ensure maintainability, scalability, and visual excellence.
The foundation of effective KMP development lies in strategic code separation. Your shared module should contain:
<em>// Shared module structure</em>
commonMain/
├── data/
│ ├── models/
│ ├── repositories/
│ └── network/
├── domain/
│ ├── usecases/
│ └── entities/
└── presentation/
├── viewmodels/
└── state/
Real-World Example: Consider a fitness tracking app. The WorkoutSession
data class, FitnessRepository
, and WorkoutAnalytics
business logic reside in the shared module. The Android UI uses Jetpack Compose with Material Design 3 components, while iOS implements SwiftUI equivalents, both consuming the same shared logic.
Material Design 3’s dynamic color system creates personalized experiences that adapt to user preferences and device capabilities. Implementation involves:
<em>// Android implementation with dynamic colors</em>
@Composable
fun AppTheme(
darkTheme: Boolean = isSystemInDarkTheme(),
dynamicColor: Boolean = true,
content: @Composable () -> Unit
) {
val colorScheme = when {
dynamicColor && Build.VERSION.SDK_INT >= Build.VERSION_CODES.S -> {
val context = LocalContext.current
if (darkTheme) dynamicDarkColorScheme(context)
else dynamicLightColorScheme(context)
}
darkTheme -> DarkColorScheme
else -> LightColorScheme
}
MaterialTheme(
colorScheme = colorScheme,
typography = AppTypography,
content = content
)
}
Material Design 3 Expressive emphasizes emotional connection through:
Case Study: A meditation app implemented Material Design 3’s emotional design principles by using soft, breathing animations for the main interface, bold confidence-building typography for achievement screens, and curious motion reveals for discovering new content. User engagement increased by 40% after implementation.
Maintaining design consistency across platforms while respecting platform conventions:
<em>// Shared component interface</em>
expect class PlatformButton {
fun create(
text: String,
onClick: () -> Unit,
style: ButtonStyle
): @Composable () -> Unit
}
<em>// Android implementation</em>
actual class PlatformButton {
actual fun create(
text: String,
onClick: () -> Unit,
style: ButtonStyle
): @Composable () -> Unit = {
Button(
onClick = onClick,
colors = ButtonDefaults.buttonColors(
containerColor = MaterialTheme.colorScheme.primary
)
) {
Text(text)
}
}
}
Aspect | Traditional Native Development | KMP with Material Design 3 |
---|---|---|
Development Time | 100% per platform | 30-40% per additional platform |
Code Reusability | 0% across platforms | 60-80% shared logic |
Design Consistency | Manual synchronization | Unified design system |
Theming Capabilities | Platform-specific implementations | Dynamic, adaptive theming |
Maintenance Overhead | High (multiple codebases) | Low (single source of truth) |
Performance | Native | Native (compiled) |
UI Expressiveness | Limited by platform defaults | Rich, expressive components |
Team Efficiency | Separate platform teams | Unified development team |
Let’s build a complete KMP app with Material Design 3 Expressive from scratch.
<em>// build.gradle.kts (shared module)</em>
kotlin {
androidTarget {
compilations.all {
kotlinOptions {
jvmTarget = "1.8"
}
}
}
listOf(
iosX64(),
iosArm64(),
iosSimulatorArm64()
).forEach {
it.binaries.framework {
baseName = "shared"
isStatic = true
}
}
sourceSets {
commonMain.dependencies {
implementation(compose.runtime)
implementation(compose.foundation)
implementation(compose.material3)
implementation(compose.ui)
implementation(compose.components.resources)
implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.7.3")
implementation("org.jetbrains.kotlinx:kotlinx-serialization-json:1.6.0")
}
androidMain.dependencies {
implementation("androidx.compose.ui:ui-tooling-preview:1.5.4")
implementation("androidx.activity:activity-compose:1.8.1")
}
}
}
<em>// theme/Color.kt</em>
val md_theme_light_primary = Color(0xFF6750A4)
val md_theme_light_onPrimary = Color(0xFFFFFFFF)
val md_theme_light_primaryContainer = Color(0xFFEADDFF)
val md_theme_light_onPrimaryContainer = Color(0xFF21005D)
val md_theme_dark_primary = Color(0xFFD0BCFF)
val md_theme_dark_onPrimary = Color(0xFF381E72)
val md_theme_dark_primaryContainer = Color(0xFF4F378B)
val md_theme_dark_onPrimaryContainer = Color(0xFFEADDFF)
val LightColors = lightColorScheme(
primary = md_theme_light_primary,
onPrimary = md_theme_light_onPrimary,
primaryContainer = md_theme_light_primaryContainer,
onPrimaryContainer = md_theme_light_onPrimaryContainer,
<em>// ... additional colors</em>
)
val DarkColors = darkColorScheme(
primary = md_theme_dark_primary,
onPrimary = md_theme_dark_onPrimary,
primaryContainer = md_theme_dark_primaryContainer,
onPrimaryContainer = md_theme_dark_onPrimaryContainer,
<em>// ... additional colors</em>
)
<em>// theme/Typography.kt</em>
val AppTypography = Typography(
displayLarge = TextStyle(
fontFamily = FontFamily.Default,
fontWeight = FontWeight.Normal,
fontSize = 57.sp,
lineHeight = 64.sp,
letterSpacing = (-0.25).sp,
),
headlineLarge = TextStyle(
fontFamily = FontFamily.Default,
fontWeight = FontWeight.Bold,
fontSize = 32.sp,
lineHeight = 40.sp,
letterSpacing = 0.sp,
),
bodyLarge = TextStyle(
fontFamily = FontFamily.Default,
fontWeight = FontWeight.Normal,
fontSize = 16.sp,
lineHeight = 24.sp,
letterSpacing = 0.5.sp,
)
)
<em>// shared/domain/TaskRepository.kt</em>
class TaskRepository {
private val tasks = mutableListOf<Task>()
suspend fun getTasks(): List<Task> {
delay(500) <em>// Simulate network call</em>
return tasks.toList()
}
suspend fun addTask(task: Task) {
tasks.add(task)
}
suspend fun updateTask(task: Task) {
val index = tasks.indexOfFirst { it.id == task.id }
if (index != -1) {
tasks[index] = task
}
}
}
<em>// shared/presentation/TaskViewModel.kt</em>
class TaskViewModel {
private val repository = TaskRepository()
private val _uiState = MutableStateFlow(TaskUiState())
val uiState: StateFlow<TaskUiState> = _uiState.asStateFlow()
fun loadTasks() {
viewModelScope.launch {
_uiState.value = _uiState.value.copy(isLoading = true)
try {
val tasks = repository.getTasks()
_uiState.value = _uiState.value.copy(
tasks = tasks,
isLoading = false
)
} catch (e: Exception) {
_uiState.value = _uiState.value.copy(
error = e.message,
isLoading = false
)
}
}
}
}
<em>// androidApp/MainActivity.kt</em>
@Composable
fun TaskScreen(viewModel: TaskViewModel) {
val uiState by viewModel.uiState.collectAsState()
LazyColumn(
modifier = Modifier
.fillMaxSize()
.padding(16.dp),
verticalArrangement = Arrangement.spacedBy(8.dp)
) {
items(uiState.tasks) { task ->
TaskCard(
task = task,
onTaskClick = { <em>/* Handle click */</em> },
modifier = Modifier.animateItemPlacement()
)
}
}
}
@Composable
fun TaskCard(
task: Task,
onTaskClick: () -> Unit,
modifier: Modifier = Modifier
) {
Card(
modifier = modifier
.fillMaxWidth()
.clickable { onTaskClick() },
elevation = CardDefaults.cardElevation(defaultElevation = 4.dp),
colors = CardDefaults.cardColors(
containerColor = MaterialTheme.colorScheme.surfaceVariant
)
) {
Column(
modifier = Modifier.padding(16.dp)
) {
Text(
text = task.title,
style = MaterialTheme.typography.headlineSmall,
color = MaterialTheme.colorScheme.onSurfaceVariant
)
Spacer(modifier = Modifier.height(4.dp))
Text(
text = task.description,
style = MaterialTheme.typography.bodyMedium,
color = MaterialTheme.colorScheme.onSurfaceVariant.copy(alpha = 0.7f)
)
}
}
}
@Composable
fun DynamicThemeExample() {
val context = LocalContext.current
val dynamicColorScheme = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
dynamicLightColorScheme(context)
} else {
LightColors
}
MaterialTheme(
colorScheme = dynamicColorScheme,
typography = AppTypography
) {
<em>// Your app content</em>
}
}
@Composable
fun ExpressiveButton(
text: String,
onClick: () -> Unit,
modifier: Modifier = Modifier
) {
var isPressed by remember { mutableStateOf(false) }
val scale by animateFloatAsState(
targetValue = if (isPressed) 0.95f else 1f,
animationSpec = spring(
dampingRatio = Spring.DampingRatioMediumBouncy,
stiffness = Spring.StiffnessLow
)
)
Button(
onClick = {
onClick()
},
modifier = modifier
.scale(scale)
.pointerInput(Unit) {
detectTapGestures(
onPress = {
isPressed = true
tryAwaitRelease()
isPressed = false
}
)
},
colors = ButtonDefaults.buttonColors(
containerColor = MaterialTheme.colorScheme.primary
)
) {
Text(
text = text,
style = MaterialTheme.typography.labelLarge
)
}
}
<em>// shared/test/TaskRepositoryTest.kt</em>
class TaskRepositoryTest {
private lateinit var repository: TaskRepository
@BeforeTest
fun setup() {
repository = TaskRepository()
}
@Test
fun `addTask should increase task count`() = runTest {
val initialCount = repository.getTasks().size
val newTask = Task("1", "Test Task", "Description")
repository.addTask(newTask)
val finalCount = repository.getTasks().size
assertEquals(initialCount + 1, finalCount)
}
}
<em>// androidApp/test/TaskScreenTest.kt</em>
@RunWith(AndroidJUnit4::class)
class TaskScreenTest {
@get:Rule
val composeTestRule = createComposeRule()
@Test
fun taskScreen_displaysTaskList() {
val mockTasks = listOf(
Task("1", "Task 1", "Description 1"),
Task("2", "Task 2", "Description 2")
)
composeTestRule.setContent {
AppTheme {
TaskList(tasks = mockTasks)
}
}
composeTestRule.onNodeWithText("Task 1").assertIsDisplayed()
composeTestRule.onNodeWithText("Task 2").assertIsDisplayed()
}
}
@Composable
fun OptimizedTaskList(
tasks: List<Task>,
modifier: Modifier = Modifier
) {
LazyColumn(
modifier = modifier,
contentPadding = PaddingValues(16.dp),
verticalArrangement = Arrangement.spacedBy(8.dp)
) {
items(
items = tasks,
key = { task -> task.id }
) { task ->
TaskCard(
task = task,
modifier = Modifier.animateItemPlacement(
animationSpec = tween(300)
)
)
}
}
}
class TaskViewModel : ViewModel() {
private val _tasks = MutableStateFlow<List<Task>>(emptyList())
val tasks: StateFlow<List<Task>> = _tasks.asStateFlow()
override fun onCleared() {
super.onCleared()
<em>// Clean up resources</em>
}
}
The convergence of KMP and Material Design 3 is accelerating several key trends:
Expect Material Design 3 to integrate machine learning capabilities that automatically adjust UI elements based on user behavior patterns and preferences.
Compose Multiplatform will mature to provide near-identical UI experiences across all platforms while maintaining native performance.
KMP’s WebAssembly target will enable sharing business logic between mobile apps and high-performance web applications.
KMP will expand to support emerging platforms including AR/VR devices, automotive systems, and IoT devices.
Material Design 3 will incorporate more sophisticated physics-based animations and haptic feedback integration.
Problem: Attempting to share too much UI logic across platforms.
Solution: Focus on sharing business logic, data models, and networking. Keep UI platform-specific for optimal user experience.
Problem: Creating identical UIs that don’t feel native to each platform.
Solution: Adapt Material Design 3 principles to respect platform-specific navigation patterns and interaction models.
Problem: Not optimizing shared code for mobile constraints.
Solution: Profile regularly, use appropriate data structures, and implement lazy loading where necessary.
Building KMP apps with Material Design 3 Expressive represents the pinnacle of modern mobile development. By combining Kotlin’s powerful multiplatform capabilities with Google’s most advanced design system, you can create applications that are not only functionally superior but also emotionally engaging and visually stunning.
The implementation strategies, code examples, and best practices outlined in this guide provide you with a solid foundation to start building your own expressive multiplatform applications. Remember that successful KMP development is about finding the right balance between code sharing and platform-specific optimization.
As Material Design 3 continues to evolve and KMP matures, early adopters will have a significant competitive advantage. Start experimenting with these technologies today, and you’ll be well-positioned to deliver the next generation of mobile applications that users love and businesses depend on.
The future of mobile development is expressive, efficient, and truly multiplatform. Your journey starts now.
About the Author: A senior Android developer with 10+ years of experience in Kotlin and cross-platform development. Specializes in Material Design implementation, KMP architecture, and performance optimization. Passionate about creating beautiful, functional applications that push the boundaries of mobile technology.
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