Lessons Learned from Using Kotlin Multiplatform internally

@bennegeek Lessons Learned from Using Kotlin Multiplatform internally JB Lorenzo
| #DCNYC19

@bennegeek Re-org

@bennegeek Poznan Berlin Shared Services

@bennegeek Poznan Berlin

@bennegeek Poznan Berlin Pack 1 Pack 2 Pack 3 Pack
4 Pack 5 Pack 6 Pack 7 Pack 8

4 Pack 5 Pack 6 Pack 7 Pack 8 Why?

4 Pack 5 Pack 6 Pack 7 Pack 8 Why? Why? Why?

4 Pack 5 Pack 6 Pack 7 Pack 8 Why? Why? Why? Why? Why? Why?

@bennegeek old API

@bennegeek old API new API

4 Pack 5 Pack 6 Pack 7 Pack 8 Why? Why? Why? Why? Why? Why?

@bennegeek Time

@bennegeek Kotlin/ MPP Time

@bennegeek Kotlin/ MPP Time Time/ Eﬀort Saved

@bennegeek Haaaave you met…

@bennegeek Kotlin/MPP Haaaave you met…

@bennegeek

@bennegeek Resistance Uncertainty Concerns Risk

@bennegeek New Concepts Existing Concept Resistance Uncertainty Concerns Risk

@bennegeek Resistance Uncertainty Concerns Risk Kotlin/MPP

@bennegeek Resistance Uncertainty Concerns Risk Kotlin/MPP On going (Internally only)
In Production

@bennegeek Kotlin/MPP

@bennegeek Android First

@bennegeek Android First app implementation project(":features:posting") implementation project(":features:posting_ui")

@bennegeek Android First

@bennegeek Android First Kotlin Serialization Time Ktor Onboard Android Devs

@bennegeek Android First Kotlin Serialization Time Ktor Onboard Android Devs
SQLDelight View Models and the rest

@bennegeek iOS

@bennegeek iOS * No control over Kotlin code * No
knowledge of Kotlin/Kotlinx * Can we run tests * Is this a transition to Kotlin * Ktor Multiplatform is "experimental" * Concerns about coupling and syncing

@bennegeek iOS * No control over Kotlin code * No
knowledge of Kotlin/Kotlinx * Can we run tests * Is this a transition to Kotlin * Ktor Multiplatform is "experimental" * Concerns about coupling and syncing Write a detailed RFC

@bennegeek iOS * Are there bigger projects? * Concerns about
learning curve * Still No control on Kotlin code * Fear of bugs * Debugging * Performance concerns

@bennegeek iOS * Are there bigger projects? * Concerns about
learning curve * Still No control on Kotlin code * Fear of bugs * Debugging * Performance concerns Limit Scope of RFC Gather support from Android devs

@bennegeek iOS * Scope is too small * Concerns about
interop not being smooth * Concerns about memory, thread, error management

@bennegeek iOS Both iOS/Android developers Android developer

@bennegeek iOS Both iOS/Android developers Android developer Continue with MPP
on Android Use only internally for iOS

@bennegeek iOS Swift/Objc iOS App

@bennegeek Models Model to Domain Mappers Interfaces Network Calls (Ktor)
iOS Kotlin/MPP Swift/Objc iOS App

@bennegeek iOS Swift/Objc iOS App Models Model to Domain Mappers
Interfaces Network Calls (Ktor) Kotlin/MPP Model to I Netwo Sw

@bennegeek iOS Models Model to Domain Mappers Interfaces Network Calls
(Ktor) Kotlin/MPP Models Model to Domain Mappers Interfaces Network Calls (Ktor) Swift

@bennegeek iOS Swift/Objc iOS App Models Model-to-Domain Mappers Interfaces Network
Calls (Ktor) Swift

@bennegeek Team Learnings

@bennegeek Technical Learnings

@bennegeek Technical Learnings Mapping Strings to Enum using Kotlin Serialization

@bennegeek Technical Learnings Threading issues on the Main Thread https://blog.usejournal.com/the-dos-and-donts-of-mobile-development-with-kotlin-multiplatform-
db7c098545c0 https://medium.com/@yuyaHorita/kotlin-native-ios-a1a73d7390fe https://proandroiddev.com/current-issues-with-kotlin-multiplatform-and-how-to-fix-them-5ae62822a546

@bennegeek Technical Learnings Error Handling @Throws fun kotlinMethod()

@bennegeek Technical Learnings Error Handling @Throws fun kotlinMethod(str: String) -
(void)kotlinMethod:(NSString *)str error:(NSError * _Nullable * _Nullable)error;

@bennegeek Technical Learnings Error Handling @Throws fun kotlinMethod(str: String) func
kotlinMethod(str: String) throws

@bennegeek Technical Learnings Project is not mono-repo, how to include
Kotlin/MPP

@bennegeek Technical Learnings Output is only 64-bit?

@bennegeek Technical Learnings Where are my dragons debugging symbols

@bennegeek Technical Learnings Where are my dragons debugging symbols https://github.com/JetBrains/kotlin-native/issues/2422
* dSYM files only for debug

@bennegeek Technical Learnings Coroutines on iOS?

@bennegeek Technical Learnings Coroutines on iOS? // common internal expect
val ApplicationScope: CoroutineScope ApplicationScope.launch { try { val ret = getCitySuggestion(query, isAdding, longitude, latitude) callback(ret, null) } catch (error: Error) { callback(null, error) } }

@bennegeek Technical Learnings Coroutines on iOS? // ios/actual.kt internal actual
val ApplicationScope: CoroutineScope = MainScope() private class MainDispatcher: CoroutineDispatcher() { override fun dispatch(context: CoroutineContext, block: Runnable) { dispatch_async(dispatch_get_main_queue()) { block.run() } } } internal class MainScope: CoroutineScope { private val dispatcher = MainDispatcher() private val job = Job() override val coroutineContext: CoroutineContext get() = dispatcher + job }

@bennegeek What’s next for us * do Workshops for MPP
* Pair iOS and Android devs * Wait for large companies to adopt Kotlin /MPP

@bennegeek What you can do * Introduce Kotlin/MPP * Make
an RFC in your team * Make devs familiar with both iOS and Android * Pair iOS and Android devs * Make your efforts public * Help Improve tooling Kotlin /MPP

@bennegeek tech.olx.com

Berlin Buenos Aires Lisbon New Delhi Poznan Dubai

@bennegeek Thank you! Any Questions? Get in touch with us
olxgroup.com tech.olx.com olxtechberlin [email protected] jblorenzo JB Lorenzo | #DCNYC19

Lessons Learned from Using Kotlin Multiplatform...

Lessons Learned from Using Kotlin Multiplatform internally

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