Kotlin Multiplatform for Android/iOS devs

Transcript

1. Kotlin Multiplatform for Android/iOS devs Paolo Rotolo Mobile developer @ Nextome Anna Labellarte Mobile developer @ Nextome
2. What is Kotlin Multiplaform
3. What is Kotlin Multiplatform
4. What is Kotlin Multiplatform
5. What is Kotlin Multiplatform Kotlin/Native • No Vi rt ual Machine • Targets • iOS • Windows, Linux, Mac • Small devices • Interop with C and obj-C Kotlin/JVM • 100 % interop with Java
6. Kotlin Multiplatform Mobile Image taken from: https://dev.to/anioutkajarkova/kotlin-multiplatform-practical-multithreading-part-1-4357 Kotlin/Native Kotlin/JVM BETA
7. Kotlin Multiplatform Mobile (KMM) BETA
8. Kotlin Multiplatform Mobile (KMM) BETA
9. KMM Roadmap 2017 Kotlin multiplatform Coroutines First class language for Android Support for iOS Alpha Beta 2018 2019 2020 2022 2022
10. Why we decided to give it a shot
11. Why we decided to give it a shot - team
12. Why we decided to give it a shot - SDK product workflow
13. Roadmap 1. Validate the idea with a small library
14. Roadmap 2. Transform the existing android project Room Retro fi t Resources DI DateTime
15. Roadmap 3. Make it work for iOS
16. Roadmap 4. Go on with multipla tf orm 5. Share as much code as we can
17. Pros & Cons ✅ Easy to use ✅ Low risks ✅ Easy integration with native code ✅ Shared codebase ✅ Active Community
18. Pros & Cons ❌ Code generated not Swi ft -friendly ❌ Build time can be slow on Xcode ❌ Few multipla tf orm libraries
19. Inside a KMM app
20. Tools Android Studio Kotlin Multipla tf orm Plugin Xcode / AppCode Kotlin Native Plugin
21. How to start
22. Root project
25. plugins { kotlin("multiplatform") kotlin("native.cocoapods") id("com.android.library") } kotlin { android() ios() }
26. kotlin { android() ios() sourceSets { val commonMain by getting { dependencies { implementation( "io.ktor:ktor-client-core:$ktor_version") } } val androidMain by getting { dependencies { implementation( "androidx.work:work-runtime-ktx:$work_version") } } val iosMain by getting } }
27. val commonMain by getting { dependencies { implementation( "io.ktor:ktor-client-core:$ktor_version") } } val androidMain by getting { dependencies { implementation( "androidx.work:work-runtime-ktx:$work_version") } } val iosMain by getting } } val commonTest by getting val androidTest by getting val iosTest by getting
30. plugins { kotlin("multiplatform") kotlin("native.cocoapods") id("com.android.library") } kotlin { android() ios() cocoapods { pod("SSZipArchive") } sourceSets { val commonMain by getting { dependencies { implementation( "io.ktor:ktor-client-core:$ktor_version" } }
31. How to write multiplatform code
32. How to write multiplatform code
33. package com.nextome.hellokmm class Greeting { private val platform: Platform = getPlatform() fun greet(): String { return "Hello, ${platform.name}!" } }
34. package com.nextome.hellokmm interface Platform { val name: String } expect fun getPlatform(): Platform
35. package com.nextome.hellokmm import android.os.Build.VERSION class AndroidPlatform : Platform { override val name: String = "Android ${VERSION.SDK_INT}" } actual fun getPlatform(): Platform = AndroidPlatform()
36. package com.nextome.hellokmm import platform.UIKit.UIDevice class IOSPlatform: Platform { override val name: String = UIDevice.currentDevice.systemName() + " " + UIDevice.currentDevice.systemVersion } actual fun getPlatform(): Platform = IOSPlatform()
37. Publish multiplatform libraries
38. / / build.gradle.kts (:shared) plugins { kotlin("multiplatform") id(“com.android.library”) }
39. / / build.gradle.kts (:shared) plugins { kotlin("multiplatform") id(“com.android.library”) id("maven-publish") } group = "com.nextome.hellokmm" version = "1.0.0"
40. // build.gradle.kts (:shared) plugins { kotlin("multiplatform") id(“com.android.library”) id("maven-publish") } group = "com.nextome.hellokmm" version = “1.0.0" kotlin { android{ publishLibraryVariants("release", "debug") } // [ ... ] }
41. ./gradlew publishToMavenLocal // build.gradle.kts (:shared) plugins { kotlin("multiplatform") id(“com.android.library”) id("maven-publish") } group = "com.nextome.hellokmm" version = “1.0.0" kotlin { android{ publishLibraryVariants("release", "debug") }
43. sourceSets { val commonMain by getting { dependencies { implementation("com.nextome.hellokmm:hellokmm:1.0.0") } } } Consume libraries
44. Useful libraries for KMM
45. Retrofit, OkHttp ➡ Ktor
46. Ktor suspend fun main() { val client = HttpClient() val response: HttpResponse = client.get("https: / / ktor.io/") println(response.status) client.close() }
47. Ktor suspend fun main() { val client = HttpClient() { install(ContentNegotiation) { json() } } val response: HttpResponse = client.get("https: / println(response.status) client.close() }
48. install(Auth) { bearer { loadTokens { bearerTokenStorage.last() } refreshTokens { val refresh = this.oldTokens.refreshToken getNewToken(refresh) } } } suspend fun main() { val client = HttpClient() { install(ContentNegotiation) { json() } }
49. bearerTokenStorage.last() } refreshTokens { val refresh = this.oldTokens.refreshToken getNewToken(refresh) } } } } / install(Logging) { logger = Logger.DEFAULT level = LogLevel.HEADERS filter { request -> request.url.host.contains("ktor.io") } }
50. / filter { request -> request.url.host.contains("ktor.io") } } HttpResponseValidator { handleResponseExceptionWithRequest { exception, request -> val clientException = exception as? ClientRequestException ?: return@handleResponseExceptionWithRequest when (clientException.response.status) { HttpStatusCode.NotFound - > { throw MissingPageException(exceptionResponse) } } } }
51. Gson, Moshi ➡ kotlinx-serialization
52. kotlinx-serialization @Serializable data class User(val name: String, val email: String) fun main() { val data = User("Paolo", “paolo@rotolo.dev”) val serializedData: String = Json.encodeToString(data) println(serializedData) // {“name”:"Paolo","email":"paolo@rotolo.dev"} val deserializedData: User = Json.decodeFromString(serializedData) println(deserializedData) // Project(name=Paolo, email=paolo@rotolo.dev) }
53. Room Rx*, LiveData Timber Hilt, Koin SqlDelight / Realm Coroutines & Flow Kermit Koin ➡ ➡ ➡ ➡ Retrofit, OkHttp Gson, Moshi ➡ Ktor ➡ kotlinx-serialization
54. SharedPreferences, DataStore -> DataStore
55. JetPack Multiplatform Libraries Compose DataStore Collections preview preview
56. The Dark side of KMM
57. Make it debuggable on iOS
63. Data Types fun insertNewTodo( title: String, priority: Int )
64. Data Types fun insertNewTodo( title: String, priority: Int ) repository.insertNewTodo( title: String, priority: ? Int32 )
65. Data Types fun insertNewTodo( title: String, priority: Int ) repository.insertNewTodo( title: String, priority: ? ) KotlinInt?
66. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } }
67. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } scope.launch { val todo = TodoRepository().fetchTodo() }
68. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } TodoRepository().fetchTodo {todos, error in } func loadTodo() async throws { let todo = try await TodoRepository().fetchTodo() }
69. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } scope.launch { val todo = TodoRepository().fetchTodo() }
70. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } scope.launch { val todo = TodoRepository().fetchTodo() } scope.cancel()
71. Koru Inspired by https://touchlab.co/kotlin-coroutines-rxswift/
72. Koru Inspired by https://touchlab.co/kotlin-coroutines-rxswift/ plugins { // add ksp and koru compiler plugin id("com.google.devtools.ksp") version "1.6.21-1.0.6" id("com.futuremind.koru").version("0.11.1") } kotlin { sourceSets { val commonMain by getting { dependencies { // add library dependency implementation("com.futuremind:koru:0.11.1") } } val iosMain by creating { ... } } } koru { nativeSourceSetNames = listOf("iosMain") }
73. Coroutines class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } }
74. Coroutines @ToNativeClass(name = "TodoRepositoryIos") class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } }
75. // build/generated/ksp/TodoRepositoryIos.kt public class TodoRepositoryIos( private val wrapped: TodoRepository, private val scopeProvider: ScopeProvider?, ) { public constructor(wrapped: TodoRepository) : this(wrapped,exportedScopeProvider_mainScopeProvider) public fun fetchTodo(): SuspendWrapper<List<Todo> = SuspendWrapper(scopeProvider, false) { wrapped.fetchTodo() } }
76. Coroutines @ToNativeClass(name = "TodoRepositoryIos") class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } }
77. Coroutines @ToNativeClass(name = "TodoRepositoryIos") class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } let repo = TodoRepositoryIos( wrapped: TodoRepository(), scope: coroutineScope) repo.getTodoWrapped().subscribe( onSuccess: { (array: NSArray?) -> () in }, onThrow: { throwable in })
78. Coroutines @ToNativeClass(name = "TodoRepositoryIos") class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } let repo = TodoRepositoryIos( wrapped: TodoRepository(), scope: coroutineScope) repo.getTodoWrapped().subscribe( onSuccess: { (array: NSArray?) -> () in }, onThrow: { throwable in }) SuspendWrapper<List<Todo >>
79. @ToNativeClass(name = "TodoRepositoryIos") class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } }
80. @ToNativeClass(name = "TodoRepositoryIos", launchOnScope = MainScopeProvider :: class) class TodoRepository { suspend fun fetchTodo(): List<Todo> { val todos = getTodoFromServer() saveToDb(todos) return todos } } @ExportedScopeProvider class MainScopeProvider : ScopeProvider { override val scope : CoroutineScope = MainScope() }
81. @ToNativeClass(name = "TodoRepositoryIos", launchOnScope = MainScopeProvider :: class) class TodoRepository { suspend fun fetchTodoList(): TodoList { val todos = getTodoFromServer() saveToDb(todos) return TodoList(todos) } } @ExportedScopeProvider class MainScopeProvider : ScopeProvider { override val scope : CoroutineScope = MainScope() } data class TodoList(val list: List<Todo>)
82. @ToNativeClass(name = "TodoRepositoryIos", launchOnScope = MainScopeProvider :: class) class TodoRepository { suspend fun fetchTodoList(): TodoList { val todos = getTodoFromServer() saveToDb(todos) return TodoList(todos) } } Coroutines let repo = TodoRepositoryIos(wrapped: TodoRepository()) repo.fetchTodoList().subscribe(onSuccess: { (list: TodoList?) in }, onThrow: { (throwable: KotlinThrowable) in })
83. @ToNativeClass(name = "TodoRepositoryIos", launchOnScope = MainScopeProvider :: class) class TodoRepository { suspend fun fetchTodoList(): TodoList { val todos = getTodoFromServer() saveToDb(todos) return TodoList(todos) } } Coroutines let repo = TodoRepositoryIos(wrapped: TodoRepository()) let job = repo.fetchTodoList().subscribe(onSuccess: { (list: TodoList?) in }, onThrow: { (throwable: KotlinThrowable) in }) job.cancel(cause: KotlinCancellationException(message: "Stop it!"))
84. Flow class RandomIntGenerator { fun generateEach(interval: Long) = flow { while(true) { delay(interval) emit(Random.nextInt()) } } }
85. Flow class RandomIntGenerator { fun generateEach(interval: Long) = flow { while(true) { delay(interval) emit(Random.nextInt()) } } } lifecycleScope.launch { RandomIntGenerator().generateEach(ONE_SECOND).collect { print(it) } }
86. Flow class RandomIntGenerator { fun generateEach(interval: Long) = flow { while(true) { delay(interval) emit(Random.nextInt()) } } } RandomIntGenerator() .generateEachTest(interval: Int64(1000)) .collect(collector: Collector()) { error in } class Collector: Kotlinx_coroutines_coreFlowCollector{ func emit(value: Any?, completionHandler: @escaping (Error?) -> Void) { print(value) completionHandler(nil) } }
87. RandomIntGenerator() .generateEachTest(interval: Int64(1000)) .collect(collector: Collector()) { error in } class Collector: Kotlinx_coroutines_coreFlowCollector{ func emit(value: Any?, completionHandler: @escaping (Error?) -> Void) { print(value) completionHandler(nil) } }
88. RandomIntGenerator() .generateEach(interval: ONE_SECOND) .collect(collector: Collector<KotlinInt>() { value in print(value) }) { (error) in print(error?.localizedDescription) } class Collector<T>: Kotlinx_coroutines_coreFlowCollector { let callback:(T) -> Void init(callback: @escaping (T) -> Void) { self.callback = callback } func emit(value: Any?, completionHandler: @escaping (Error?) -> Void) { callback(value as! T) completionHandler(nil) } }
89. class RandomIntGenerator { fun generateEach(interval: Long) = flow { while(true) { delay(interval) emit(Random.nextInt()) } } }
90. class RandomIntGenerator { fun generateEach(interval: Long) = flow { while(true) { delay(interval) emit(Random.nextInt()) } } } fun <T> Flow<T>.wrap(): CFlow<T> = CFlow(this) class CFlow<T>(private val origin: Flow<T>) : Flow<T> by origin { fun watch(block: (T) -> Unit): Closeable { val job = Job() onEach { block(it) }.launchIn(CoroutineScope(Dispatchers.Main + job)) return object : Closeable { override fun close() { job.cancel() } } } }
91. class RandomIntGenerator { fun generateEach(interval: Long): CFlow<Int> = flow { while(true) { delay(interval) emit(Random.nextInt()) } }.wrap() } fun <T> Flow<T>.wrap(): CFlow<T> = CFlow(this) class CFlow<T>(private val origin: Flow<T>) : Flow<T> by origin { fun watch(block: (T) > val job = Job() onEach { block(it) }.launchIn(CoroutineScope(Dispatchers.Main + job)) return object : Closeable { override fun close() { job.cancel() } } } }
92. class RandomIntGenerator { fun generateEach(interval: Long): CFlow<Int> = flow { while(true) { delay(interval) emit(Random.nextInt()) } }.wrap() } RandomIntGenerator() .generateEach(interval: ONE_SECOND) .watch { (value: KotlinInt?) in print(value) }
93. let disposable = RandomIntGenerator() .generateEach(interval: ONE_SECOND) .watch { (value: KotlinInt?) in print(value) } disposable.close() class RandomIntGenerator { fun generateEach(interval: Long): CFlow<Int> = flow { while(true) { delay(interval) emit(Random.nextInt()) } }.wrap() }
94. Error Handling UNCHECKED EXCEPTIONS CHECKED EXCEPTIONS
95. Error Handling
96. Error Handling
97. Error Handling
98. Error Handling
99. Error Handling
100. Error Handling
101. Error Handling
102. Default parameters
103. Default parameters
104. Default parameters
105. Default parameters
106. Sealed Class
107. Sealed Class
108. Sealed Class when (uiState) { is UIState.Data -> TODO() is UIState.Error - > TODO() is UIState.Loading - > TODO() }
109. Sealed Class
110. Sealed Class Enum
112. Sealed Class
113. In the end… Share common logic in Kotlin Work together to make it work be tt er!
114. In the end… Share common logic in Kotlin Work together to make it work be tt er! Sometimes it could be ugly but we’re ge tt ing there (fast)
115. Thanks!