Magic and Tricks with Kotlin Multiplatform

This talk is for mobile engineers that have experience with Swift or Kotlin for iOS and Android We will cover the getting started guide for all the developers that are interested in moving to Kotlin Multiplatform as a production-ready tool, taking into consideration all the pitfalls and advantages we can have using it, we will cover some simple clever things you can do with Ktor and SQLiteDelight to simplify modularization, take advantages of Serialization, and the terrific world of Kotlin Multiplatform. Talking about how to shape your architecture for a production app, and sharing your architecture, without leaving behind the OS, the security and the performance of your app, sometimes we forgot that for a good production app we need a good architecture that is testable, that is taking consideration of concurrency and databases.

Transcript

1. Magic and tricks: with Kotlin Multiplatform Dinorah Tovar Unidos compartiendo y aprendiendo #SGVirtual
2. DISCLAIMER!
3. KOTLIN
 IS COOL
4. KOTLIN MULTIPLATFORM 
 IS COOLER
5. KOTLIN IS A JVM LANGUAGE, NOT AN ANDROID LANGUAGE
6. WHAT THE HECK IS KMP?
7. TRY IT BEFORE YOU BUY IT FULL OPTIONAL
8. SHARING CODE
9. SO, IS CROSS-PLATFORM? OR A FRAMEWORK KINDA CROSS
10. ONLY LOGIC, NO UI
11. ONLY LOGIC, “NO UI”
13. SO, WHAT THE HECK IS? IS A FRAMEWORK? A SDK? A PLUGIN?
14. “Kotlin's philosophy is that you don't have to migrate the entire application. Start from a easy place”
 
 -Jetbrains IS A SDK!
15. SHARED BUSINESS LOGIC
16. SHARED BUSINESS LOGIC • Not restrictions •Appearance and behavior is the same •Performance is fully Native!
17. 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
18. HOW DOES IT WORK?
19. KOTLIN MULTIPLATFORM Kotlin 
 Compiler Kotlin
 Multiplatform Native JS JVM JAR/AAR (For Android) JS (For React or Node) Binaries (For iOS)
20. KOTLIN MULTIPLATFORM
21. 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 {
22. 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
23. I DON’T GET IT, SHARING CODE? HOW?
24. 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
25. KOTLIN MULTIPLATFORM
26. EXAMPLE •The most primitive way to save a primitive variable in Android and iOS is: SharedPreferences and NSUserDefaults
27. 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.
28. 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" ) }
29. MULTITHREADING
30. SAY HI TO KTOR! Ktor Kotlin Serialization Coroutines Retrofit Kotlin Serialization Coroutines /RxJava Alamofire RxSwift/ Composite Decode/ Encode/ etc…
31. HTTP CLIENT // commonMain expect val engine: HttpClientEngine // androidMain actual val engine by lazy { Android.create() } // iosMain actual val engine by lazy { Ios.create() }
32. HTTP CLIENT class GetDogsRepository { private val client = HttpClient(engine) { install(JsonFeature) { serializer = KotlinxSerializer().apply { register(Dogs.serializer().list) } } } suspend fun getDogs(): List<Dogs> = client.get("https://www.dogs.com.mx/isleofdogs") }
33. COROUTINES SUPPORT! expect open class MyViewModel() { val clientScope: CoroutineScope protected open fun onCleared() } actual open class MyViewModel actual constructor(): ViewModel()
34. COROUTINES SUPPORT FOR IOS… KINDA Coroutines Hot Streams Cold Streams
35. 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() } } } }
36. OKIO AND OKHTTP
37. OKIO AND OKHTTP
38. DATABASES
39. SAY HI TO SQLITEDELIGHT! •Databases are hard! •SQLDelight generates typesafe APIs from your SQL statements •Android and iOS use SQL
40. 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');
41. 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<Dogs> = db.selectAll().executeAsList() }
42. FIREBASE
43. FIREBASE PLUGIN
44. GRAPHQL
45. 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
46. APOLLO FOR MULTIPLATFORM
47. APOLLO FOR MULTIPLATFORM •Apollo Runtime [Android] •Apollo API [iOS] •You can now add your schema.json and other graphql files under src/commonMain/graphql
48. THE REAL QUESTION?, IS READY FOR PROD?
49. WAIT FOR THE FUTURE
50. Magic and tricks: with Kotlin Multiplatform Unidos compartiendo y aprendiendo #SGVirtual Dinorah Tovar Lead Mobile Engineer @ddinorahtovar @ddinorahtovar @dinorahto @dinorahto