Magic and tricks: with Kotlin Multiplatform Dinorah Tovar Unidos compartiendo y aprendiendo #SGVirtual 

DISCLAIMER! 

KOTLIN
 IS COOL 

KOTLIN MULTIPLATFORM 
 IS COOLER 

KOTLIN IS A JVM LANGUAGE, NOT AN ANDROID LANGUAGE 

WHAT THE HECK IS KMP? 

TRY IT BEFORE YOU BUY IT FULL OPTIONAL 

SHARING CODE 

SO, IS CROSS-PLATFORM? OR A FRAMEWORK KINDA CROSS 

ONLY LOGIC, NO UI 

ONLY LOGIC, “NO UI” 

No content

SO, WHAT THE HECK IS? IS A FRAMEWORK? A SDK? A PLUGIN? 

“Kotlin's philosophy is that you don't have to migrate the entire application. Start from a easy place”
 
 -Jetbrains IS A SDK! 

SHARED BUSINESS LOGIC 

SHARED BUSINESS LOGIC • Not restrictions •Appearance and behavior is the same •Performance is fully Native! 

ANDROID AND IOS ARE KINDA THE SAME, RIGHT? •They are “Unix like” •They have multithreading operations •They have file/primitive saving of data and pretty much, they use SQL 

HOW DOES IT WORK? 

KOTLIN MULTIPLATFORM Kotlin 
 Compiler Kotlin
 Multiplatform Native JS JVM JAR/AAR (For Android) JS (For React or Node) Binaries (For iOS) 

KOTLIN MULTIPLATFORM 

KOTLIN MULTIPLATFORM sourceSets { commonMain { dependencies { api project(":common-all") implementation 'org.jetbrains.kotlin:kotlin-stdlib-common' --- } } commonTest { dependencies { implementation "org.jetbrains.kotlin:kotlin-test-common" --- } } androidMain { dependsOn commonMain dependencies { 

commonTest { dependencies { implementation "org.jetbrains.kotlin:kotlin-test-common" --- } } androidMain { dependsOn commonMain dependencies { implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version" --- } } iOSMain { dependsOn commonMain dependencies { implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core-native: $coroutines_version" ---- } } } KOTLIN MULTIPLATFORM 

I DON’T GET IT, SHARING CODE? HOW? 

KOTLIN MULTIPLATFORM •Use a Plugin in your grade to configure your “blocks” •We configure a Kotlin block, with our targets! One for Android and one for iOS 

KOTLIN MULTIPLATFORM 

EXAMPLE •The most primitive way to save a primitive variable in Android and iOS is: SharedPreferences and NSUserDefaults 

EXAMPLE •The most primitive way to save a primitive variable in Android and iOS is: SharedPreferences and NSUserDefaults •Kotlin only knows how to compile Kotlin code into different targets but you can make Kotlin aware of this by using the expect/actual mechanism. 

SAVING VALUES //Common Code expect fun saveValueLocally(value: String) //Android Code actual fun saveValueLocally(value: String) { //Create shared preferences sharedPreferences.edit { putString("Value", value) } } //iOS Code actual fun saveValueLocally(value: String) { NSUserDefaults.standardUserDefaults.setValue( value, forKey = "Value" ) } 

MULTITHREADING 

SAY HI TO KTOR! Ktor Kotlin Serialization Coroutines Retrofit Kotlin Serialization Coroutines /RxJava Alamofire RxSwift/ Composite Decode/ Encode/ etc… 

HTTP CLIENT // commonMain expect val engine: HttpClientEngine // androidMain actual val engine by lazy { Android.create() } // iosMain actual val engine by lazy { Ios.create() } 

HTTP CLIENT class GetDogsRepository { private val client = HttpClient(engine) { install(JsonFeature) { serializer = KotlinxSerializer().apply { register(Dogs.serializer().list) } } } suspend fun getDogs(): List = client.get("https://www.dogs.com.mx/isleofdogs") } 

COROUTINES SUPPORT! expect open class MyViewModel() { val clientScope: CoroutineScope protected open fun onCleared() } actual open class MyViewModel actual constructor(): ViewModel() 

COROUTINES SUPPORT FOR IOS… KINDA Coroutines Hot Streams Cold Streams 

COROUTINES SUPPORT FOR IOS… KINDA actual open class MyViewModel actual constructor() { private val viewModelJob = SupervisorJob() val viewModelScope: CoroutineScope = CoroutineScope(IosMainDispatcher + viewModelJob) actual val clientScope: CoroutineScope = viewModelScope protected actual open fun onCleared() { viewModelJob.cancelChildren() } object IosMainDispatcher : CoroutineDispatcher() { override fun dispatch(context: CoroutineContext, block: Runnable) { dispatch_async(dispatch_get_main_queue()) { block.run() } } } } 

OKIO AND OKHTTP 

OKIO AND OKHTTP 

DATABASES 

SAY HI TO SQLITEDELIGHT! •Databases are hard! •SQLDelight generates typesafe APIs from your SQL statements •Android and iOS use SQL 

SAY HI TO SQLITEDELIGHT! CREATE TABLE dogs ( dogName TEXT NOT NULL, dogRace TEXT NOT NULL ); 
 insert: INSERT INTO dogs (dogName, dogRace) VALUES ('Spots', 'Best friend'); 

FULL SUPPORT FOR IOS AND ANDROID class DogsDao(database: Dogs) { private val db = database.dogsModelQueries internal fun insert(item: Dogs) { db.insertItem( dogName = item.dogName, dogRace = item.dogRace ) } internal fun select():List = db.selectAll().executeAsList() } 

FIREBASE 

FIREBASE PLUGIN 

GRAPHQL 

APOLLO FOR MULTIPLATFORM •Apollo queries can be really complicated •One wrong detail in the query and there will be nothing in the tree to search 

APOLLO FOR MULTIPLATFORM 

APOLLO FOR MULTIPLATFORM •Apollo Runtime [Android] •Apollo API [iOS] •You can now add your schema.json and other graphql files under src/commonMain/graphql 

THE REAL QUESTION?, IS READY FOR PROD? 

WAIT FOR THE FUTURE 

Magic and tricks: with Kotlin Multiplatform Unidos compartiendo y aprendiendo #SGVirtual Dinorah Tovar Lead Mobile Engineer @ddinorahtovar @ddinorahtovar @dinorahto @dinorahto