How Kotlin Multiplatform was implemented in Profi

Hello, Habr! I am Misha Ignatov, team lead in the Pro company. My team is responsible for client-side mobile apps for Android and iOS. We have been using Kotlin Multiplatform in production since 2019. I'll tell you why we chose this particular technology, how we introduced it, what key stages we went through and what conclusions we made.

Briefly about Kotlin Multiplatform

Kotlin Multiplatform , Kotlin, . 2020 JetBrains Kotlin Multiplatform Mobile () — SDK, Android iOS. —  -. UI- , .

Kotlin Multiplatform

- . , React Native Flutter , . Kotlin Multiplatform . 

1. 
   
   
   
   

   , Kotlin, . . Android jar aar-, iOS — Universal Framework. .

   
   
   
   
   

2. Kotlin Swift

   
   
   
   
   

   iOS-. — . , , .

   
   
   
   
   

3. 
   
   
   
   

   - . 70% , . , , . , , — Android Kotlin iOS Swift. — - UX ( : , , , ..).

   
   
   
   
   

. , . — , . , .

1.

— API-, .  

GraphQL. — multiline . , . , . , - . «» . . 

«» . . , «» .

. Android- shared. - object



, . — iOS-.

package ru.profi.shared.queries.client.city

/**
*     [Params.term]
*/
object GeoSelectorWarpQuery : WarpQuery<Params> {

   override val hash: String? = "\$GQLID{c9d4adbb7b9ef49fc044064b9a3e662b}"

   override val dirtyQuery = listOf("\$term").let { (term) ->
       """
       query geoSelector($term: String) {
         suggestions: simpleGeoSelector(term: $term, first: 100) {
           edges {
             node {
               name
               geoCityId
               regionName
               hostname
               countryId
             }
           }
         }
       }
       """
   }.trimIndent()
}
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

override fun getQuery() = GeoSelectorWarpQuery.getQuery()
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

import KotlinComponents

struct GraphQLWarpRequests {

    static let GeoSelectorWarpQuery = GeoSelectorWarpQuery()
		...
}

let model = GraphQLRequestModel(query: GraphQLWarpRequests.GeoSelectorWarpQuery.getQuery(), variables: variables)
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

. , . iOS 0,8 . «» . 

, Kotlin. , pull request backend. , .

Kotlin ultiplatform. .

2. SDK

in-house Clickhouse. backend API . . , , , , .

. network client — ktor. . 

, . SQLDelight — . 

kotlinx.coroutines. kotlinx.serialization.

, unit-. , .

Android , iOS «» . XCode Firebase Crashlytics . , .

, CrashKiOS Touchlab. CoroutineExceptionHandler, . 

, . «». — CoroutineScope



.

Kotlin Multiplatform . SDK .

3. - Android

, , . , , .

iOS - . . — Objective-C . , .

Android - Kotlin. iOS.

IceRock.dev. , KMM . .

1. Kotlin Multiplatform gradle-.
   
   , , sourceSets .

   
   
   
   
   

2. - commonMain.
   
   , JVM Android, commonMain
   
   
   
   . , .

   
   
   
   
   

3. JVM/Android .
   
   org.json kotlinx.serialization JodaTime klock. expect/actual
   
   
   
   .

   
   
   
   
   

4. commonMain JVM- , .
   
   , JVM IOException



kotlin.Exception
   
   
   
   , ConcurrentHashMap
   
   
   
   Stately.

   
   
   
   
   

5. commonMain Android- , .
   
   Android SDK Service
   
   
   
   , WebSocket
   
   
   
   . Kotlin . 

   
   
   
   
   

   SocketService
   
   
   
   .

   
   
   
   
   
   SocketService

   interface SocketService {
   
       /**
        *     [chatUrl].        [callback]
        */
       fun connect(chatUrl: String, callback: (SocketEvent) -> Unit)
   
       /**
        *      .
        */
       fun disconnect()
   
       /**
        *   [msg]     
        */
       fun send(msg: String)
   }
   
         
         
   
           
           
           
         
   
       
           
           
           
         
         
   
           
           
           
         
   
       
       

6. API .
   
   iOS runtime- Kotlin, SDK callback onError
   
   
   
   . .

   
   
   
   
   

- . .

IceRock.dev . .

Kotlin Multiplatform - . UI UX . , - , .

. Kotlin Multiplatform — iOS . Android- iOS. , . 

. Android- build- . . iOS- , Gradle. .

— iOS. , , iOS . . Kotlin , .

. , KMM , . Kotlin Multiplatform . . Slack Telegram, Kotlin Multiplatform.

, . , . , . . , . 

Now we already have 10 common modules of varying complexity, and we continue to move business logic into common code. I am sure that Kotlin Multiplatform Mobile is ready to conquer the world of mobile application development.