Droidcon London: Navigation in a Multiplatform World

Navigation in mobile, desktop, and web applications is such a fundamental part of how we structure our architecture. In order to both obtain functional clarity, and abstraction from platform level implementation.

For a long time, there have been options available specific to each platform, and even options part of the platform framework itself. Though it can be difficult to find the right option for platform-agnostic code, ensuring consistency. Some go one step further, providing an opinionated guide on how to architecture your application.

In this talk, I'll evaluate the options available, how they differ, and to what type of applications they are best suited. Including how to get started with them, and the best practice guidelines on how to get the most out of them, for your application.

Transcript

1. Navigation in a Multiplatform World Choosing the Right Framework for your App Droidcon London - November '24 ! Ash Davies - SumUp Android & Kotlin GDE Berlin ashdavies.dev
2. blog.google/products/chrome/help-me-out-how-to-organize-chrome-tabs
3. ! ashdavies.dev
4. val history = ArrayDeque<Screen>() history.addLast(ForwardScreen) history.removeLast() ashdavies.dev
5. It's Complicated ashdavies.dev
6. ® ashdavies.dev
7. m3.material.io/components/navigation-bar/overview
8. satukyrolainen.com/affordances
9. ashdavies.dev
10. android-developers.googleblog.com/2022/05/form-factors-google-io-22.html
11. learn.microsoft.com/en-us/windows/apps/design/basics/navigation-history-and-backwards-navigation
12. ↑ ← ashdavies.dev
13. ⃕ ! ashdavies.dev
14. medium.com/androiddevelopers/the-deep-links-crash-course-part2-deep-links-from-zero-to-hero-37f94cc8fb88
15. ashdavies.dev
16. ashdavies.dev/talks/navigation-and-the-single-activity-berlin
17. "Once we have gotten in to this entry-point to your UI, we really don't care how you organise the flow inside." — Dianne Hackborn, Android Framework team, 2016 ashdavies.dev
18. Jetpack Navigation ashdavies.dev
19. Fragments ashdavies.dev
20. 2019 en.wikipedia.org/wiki/2019
21. 2014: mortar & flow github.com/square/mortar developer.squareup.com/blog/simpler-android-apps-with-flow-and-mortar
22. ashdavies.dev
23. square/workflow square.github.io/workflow ashdavies.dev
24. square.github.io/workflow/historical/
25. 2016: uber/ribs github.com/uber/RIBs uber.com/en-GB/blog/new-rider-app-architecture
26. Moving On... ashdavies.dev
27. Compose UI github.com/androidx/ androidx/tree/androidx- main/compose/ui ashdavies.dev
28. Compose UI • Declarative UI Framework • Open Source Kotlin • Accelerate UI development • Intuitive Idiomatic API ashdavies.dev
29. Obligatory Notice Compose != Compose UI ashdavies.dev
30. Compose is, at its core, a general- purpose tool for managing a tree of nodes of any type ... a “tree of nodes” describes just about anything, and as a result Compose can target just about anything. — Jake Wharton jakewharton.com/a-jetpack-compose-by-any-other-name
32. Jetpack Navigation Compose v2.4.0 (2021) • Build a navigation graph with a @Composable Kotlin DSL • Compose viewModel() scoped to navigation destination • Desintation level scope for rememberSaveable() • Automatic back handling support ashdavies.dev
33. Jetpack Navigation Compose < v2.8.0 private const val HOME_ROUTE = "home" NavHost( navController = navController, startDestination = HOME_ROUTE, ) { composable(route = HOME_ROUTE) { HomeScreen( onBackClick = navController::popBackStack, /* ... */ ) } } ashdavies.dev
34. Jetpack Navigation Compose < v2.8.0 private const val DETAIL_ID_KEY = "detailId" private const val DETAIL_ROUTE = "detail" NavHost( navController = navController, startDestination = DETAIL_ROUTE, ) { composable( route = DETAIL_ROUTE, arguments = listOf( navArgument(DETAIL_ID_KEY) { type = NavType.StringType defaultValue = null nullable = true } ) ) { DetailScreen(/* ... */) } } ashdavies.dev
35. Jetpack Navigation Compose < v2.8.0 private const val DETAIL_ID_KEY = "detailId" fun NavController.navigateToDetail(detailId: String) { navigate("detail?$DETAIL_ID_KEY=$detailId") } savedStateHandle.getStateFlow(DETAIL_ID_KEY, null) ashdavies.dev
36. Jetpack Navigation Compose v2.8.0 (04.09.2024) @Serializable data class DetailRoute(val id: String) NavHost( navController = navController, startDestination = "detail", ) { composable<DetailRoute> { DetailScreen(/* ... */) } } val route = savedStateHandle.toRoute<DetailRoute>() ashdavies.dev
37. medium.com/androiddevelopers/type-safe-navigation-for-compose-105325a97657
38. Navigation in a Multiplatform World Choosing the Right Framework for your App Android Navigation für N00bs by Some Dude ashdavies.dev
39. Kotlin Multiplatform Stable (1.9.20) ashdavies.dev
40. The Before-Times ashdavies.dev
41. The Before Times ashdavies.dev
42. ashdavies.dev
43. blog.jetbrains.com/kotlin/2023/04/kotlinconf-2023-opening-keynote/
44. ashdavies.dev
45. Maven Group ID Latest Update Stable Release Alpha Release annotation 30.10.2024 1.9.1 - collection 30.10.2024 1.4.5 1.5.0-alpha05 datastore 01.05.2024 1.1.1 - lifecycle 30.10.2024 2.8.7 2.9.0-alpha06 paging 07.08.2024 3.3.2 - room 30.10.2024 2.6.1 2.7.0-alpha11 sqlite 30.10.2024 2.4.0 2.5.0-alpha11 developer.android.com/kotlin/multiplatform | As of 01.11.2024
46. kotlin { sourceSets.commonMain.dependencies { implementation( "androidx.lifecycle:" + "lifecycle-viewmodel-ktx:" + "2.8.5" ) } } // Backed by ViewModelImpl public expect abstract class ViewModel cs.android.com/androidx/platform/frameworks/support/+/androidx-main:lifecycle/lifecycle-viewmodel/src/commonMain/kotlin/androidx/lifecycle/ ViewModel.kt
47. Multiplatform Architecture ashdavies.dev
48. Decompose & Essenty arkivanov.github.io/Decompose ashdavies.dev
49. import com.arkivanov.decompose.ComponentContext class DefaultRootComponent( componentContext: ComponentContext, ) : RootComponent, ComponentContext by componentContext { init { lifecycle... // Access the Lifecycle stateKeeper... // Access the StateKeeper instanceKeeper... // Access the InstanceKeeper backHandler... // Access the BackHandler } } ashdavies.dev
50. class RootComponent(context: ComponentContext) : Root, ComponentContext { private val navigation = StackNavigation<Config>() override val childStack = childStack(/* ... */) fun createChild(config: Config, context: ComponentContext): Child = when (config) { is Config.List -> Child.List(ItemListComponent(context) { navigation.push(Config.Details(itemId = it)) } ) is Config.Details -> /* ... */ } } private sealed class Config : Parcelable { @Parcelize object List : Config() @Parcelize data class Details(val itemId: Long) : Config() } ashdavies.dev
51. Decompose • com.arkivanov.decompose:extensions-compose • com.arkivanov.decompose:extensions-android • com.arkivanov.essenty:state-keeper ashdavies.dev
52. Compose Multiplatform ashdavies.dev
53. Compose Multiplatform v1.0 | 2021 ashdavies.dev
54. Platform Stability level Android Stable iOS Stable Desktop (JVM) Stable Server-side (JVM) Stable Web based on Kotlin/Wasm Alpha Web based on Kotlin/JS Stable watchOS Best effort tvOS Best effort ashdavies.dev
55. Compose Multiplatform Jetpack Compose 1.6.11 1.6.7 1.6.10 1.6.7 1.6.2 1.6.4 1.6.1 1.6.3 ... jetbrains.com/help/kotlin-multiplatform-dev/compose-compatibility-and-versioning.html
56. github.com/JetBrains/compose-multiplatform-core
57. kotlin { sourceSets.commonMain.dependencies { implementation("org.jetbrains.androidx.navigation:navigation-compose:2.8.0-alpha10") } } @Serializable data object HomeRoute NavHost(navController, HomeRoute) { composable<HomeRoute> { HomeScreen() } } val route = savedStateHandle.toRoute<HomeRoute>() ashdavies.dev
58. jetbrains.com/help/kotlin-multiplatform-dev/compose-navigation-routing.html
59. Compose Multiplatform Migration • Change artifact coordinates • Do nothing • Profit ashdavies.dev
60. The early bird gets the worm ... but the second mouse gets the cheese ashdavies.dev
61. Reactive Architecture • Push (not pull) • Unidirectional Data Flow • Declarative • Idempotent ashdavies.dev
62. Architecture Callbacks downloadManager.downloadFile("https://.../") { result -> fileManager.saveFile("storage/file", result) { success -> if (success) println("Downloaded file successfully") } } ashdavies.dev
63. Architecture Observables downloadManager.downloadFile("https://.../") .flatMap { result -> fileManager.saveFile("storage/file", result) } .observe { success -> if (success) println("Downloaded file successfully") } ashdavies.dev
64. Architecture Coroutines val file = downloadFile("https://.../") val success = fileManager.saveFile("storage/file", file) if (success) println("Downloaded file successfully") ashdavies.dev
65. Architecture Coroutines (Again) downloadManager.downloadFile("https://.../") .flatMapLatest { state -> when (state) { is State.Loaded -> stateFileManager.saveFile("storage/file", state.value) else -> state } } .collect { state -> when (state) { is State.Loading -> /* ... */ is State.Saved -> println("Downloaded file successfully") } } ashdavies.dev
66. Architecture Compose ashdavies.dev
67. Architecture Compose val downloadState = downloadManager .downloadFile("https://.../") .collectAsState(State.Loading) val fileState = when(downloadState) { is State.Loaded -> stateFileManager.saveFile("storage/file", state.value) else -> state } when (fileState) { is State.Loading -> /* ... */ is State.Saved -> LaunchedEffect(fileState) { println("Downloaded file successfully") } } ashdavies.dev
68. cashapp/molecule ashdavies.dev
69. Molecule fun CoroutineScope.launchCounter(): StateFlow<Int> { return launchMolecule(mode = ContextClock) { var count by remember { mutableStateOf(0) } LaunchedEffect(Unit) { while (true) { delay(1_000) count++ } } count } } ashdavies.dev
70. Demystifying Molecule Droidcon NYC 2022 ashdavies.dev/talks/demystifying-molecule-nyc
71. Role of Architecture ashdavies.dev
72. Pre-Compose Era ashdavies.dev
73. slackhq/circuit github.com/slackhq/circuit ashdavies.dev
74. Circuit • Supports most supported KMP platforms • Compose first architecture • Presenter & UI separation • Unidirectional Data Flow ashdavies.dev
75. Circuit State @Parcelize data object HomeScreen : Screen { data class State( val title: String, ): CircuitUiState } ashdavies.dev
76. Circuit Presenter class HomePresenter : Presenter<HomeScreen.State> { @Composable override fun present(): HomeScreen.State { return HomeScreen.State("Hello World") } } ashdavies.dev
77. Circuit UI @Composable fun HomeScreen( state: HomeScreen.State, modifier: Modifier = Modifier, ) { Text( text = state.title, modifier = modifier, ) } ashdavies.dev
78. Circuit val circuit = Circuit.Builder() .addPresenter<HomeScreen, HomeScreen.State>(HomePresenter()) .addUi<LauncherScreen, LauncherScreen.State> { _, _ -> HomeScreen(state, modifier) } .build() CircuitCompositionLocals(circuit) { val backStack = rememberSaveableBackStack(HomeScreen) NavigableCircuitContent( navigator = rememberCircuitNavigator(backStack), backStack = backStack, ) } ashdavies.dev
79. Circuit Navigation @Parcelize data object HomeScreen : Screen { data class State( val title: String, val eventSink: (Event) -> Unit ): CircuitUiState sealed interface Event { data class DetailClicked( val id: String, ): Event } ashdavies.dev
80. Circuit Navigation class HomePresenter(private val navigator: Navigator) : Presenter<HomeScreen.State> { @Composable override fun present(): HomeScreen.State { return HomeScreen.State("Hello World") { event -> when (event) { is HomeScreen.Event.DetailClicked -> navigator.goTo(DetailScreen(event.id)) } } } } ashdavies.dev
81. youtube.com/watch?v=ZIr_uuN8FEw
82. CircuitX • com.slack.circuit:circuitx-android • com.slack.circuit:circuitx-effects • com.slack.circuit:circuitx-gesture-navigation • com.slack.circuit:circuitx-overlays ashdavies.dev
83. rememberRetained() ashdavies.dev
84. repeatOnLifecycle() ashdavies.dev
85. collectAsStateWithLifecycle() ashdavies.dev
86. ViewModel() ashdavies.dev
87. ViewModel() !!! ashdavies.dev
88. presenterOf { val isFeatureEnabled by produceRetainedState(false) { value = TODO("Expensive Operation...") } // or rememberRetained { } ScreenState(isFeatureEnabled) } slackhq.github.io/circuit/api/0.x/circuit-retained/com.slack.circuit.retained/produce-retained-state.html
89. rememberRetained() vs rememberSaveable() ashdavies.dev
90. rememberRetainedCoroutineScope() Retaining Beyond ViewModels chrisbanes.me/posts/retaining-beyond-viewmodels
91. Circuit Examples • Chris Banes: Tivi github.com/chrisbanes/tivi • Zac Sweers: CatchUp github.com/ZacSweers/CatchUp • Zac Sweers: FieldSpottr github.com/zacsweers/fieldspottr • Ash Davies: Playground github.com/ashdavies/playground.ashdavies.dev ashdavies.dev
92. Full Disclosure Bias ashdavies.dev
93. adrielcafe/voyager voyager.adriel.cafe ashdavies.dev
94. Voyager class PostListScreen : Screen { @Composable override fun Content() { // ... } @Composable private fun PostCard(post: Post) { val navigator = LocalNavigator.currentOrThrow Card( modifier = Modifier.clickable { navigator.push(PostDetailsScreen(post.id)) } ) { // ... } } } ashdavies.dev
95. Voyager interface ParcelableScreen : Screen, Parcelable // Compile @Parcelize data class Post(/*...*/) : Parcelable @Parcelize data class ValidScreen( val post: Post ) : ParcelableScreen { // ... } // Not compile data class Post(/*...*/) @Parcelize data class ValidScreen( val post: Post ) : ParcelableScreen { // ... } ashdavies.dev
96. appyx bumble-tech.github.io/appyx ashdavies.dev
97. PreCompose github.com/Tlaster/PreCompose ashdavies.dev
98. Comparison androidx circuit decompose voyager workflow Multiplatform ✅ ✅ ✅ ✅ ✅ Compose 1st ❌ ✅ ❌ ✅ ❌ Documented* ❌ ✅ ✅ ✅ ❌ Ease-of-Use** ❌ ✅ / ✅ ❌ Opinionated*** ❌ ✅ ❌ ❌ ✅ * Documentation exists, but is outdated or hard to find ** Subjective, how quick to get started *** Additional API surface ashdavies.dev
99. Y Tho? ashdavies.dev
100. Good Code == Removable Code Code your own obscolescance ashdavies.dev
101. Thank You! Ash Davies - SumUp Android / Kotlin GDE Berlin