Kotlin Multiplatform for iOS Developers (Lightning talk)

In this talk, we will check some tricks inside the incredible world of Kotlin Multiplatform for iOS. Kotlin Multiplatform Mobile (KMM) is an SDK that allows you to use the same business logic code in both iOS and Android applications.

Transcript

1. Kotlin Multiplatform
   for iOS Developers
   Dinorah Tovar
   Platform Mobile Engineer
   @ konfío.mx
   @ddinorahtovar
   @ddinorahtovar
   

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2. Kotlin and Swift are
   like cousins
   

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3. Like cousins?
   @ddinorahtovar
   public var description: String {
   
   switch self {
   
   case .active:
   
   return "active"
   
   case .offer:
   
   return "offer"
   
   case .uploadDocuments:
   
   return "documents"
   
   case .waitingDisbursement:
   
   return "waitingDisbursement"
   
   case .former:
   
   return "former"
   
   }
   
   }
   fun description(it: String) =
   
   when (this) {
   
   active #-> "active"
   
   offer #-> "offer"
   uploadDocuments #-> “documents"
   
   waitingDisbursement #->
   “waitingDisbursement"
   
   former #-> “former”
   
   }
   

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4. Kotlin is not for Android
   only
   

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5. Kotlin is for multiple
   things!
   

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6. Kotlin is for Multiple things
   @ddinorahtovar
   Mobile Cross
   platform
   Server Side Android
   Native Web Development Data Science
   

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7. KMP is for Business Logic
   @ddinorahtovar
   KMP
   Business Logic Models
   

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8. Kotlin is for Multiple things
   @ddinorahtovar
   JAR/AAR (For Android)
   Kotlin
   Multiplatform
   Kotlin Compiler
   
   Native
   JS
   JVM
   
   Binaries for iOS
   Or Windows
   

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9. Kotlin is for Multiple things
   @ddinorahtovar
   Native
   
   Binaries for iOS
   Relies on Objective C
   
   Objective-C headers that are annotated for Swift
   

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10. What to expect from KMP
    @ddinorahtovar
    Name Folder Target Result
    Common
    iOS
    Android
    SharedCode/commonMain/kotlin
    SharedCode/iosMain
    SharedCode/androidMain/kotlin
    -
    iOS arm 64
    or
    x86_64
    JVM 1.6
    Kotlin metadata
    Apple framework
    .jar file or
    .class files
    

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11. What to expect from KMP
    @ddinorahtovar
    Kotlin Multiplatform
    First Gen Support
    Android and iOS
    SDK
    

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12. Sharing the logic!
    @ddinorahtovar
    expect fun / class
    
    actual fun / class declaration
    
    Import iOS libraries
    
    actual fun / class declaration
    
    Import JVM libraries
    
    

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13. Sharing the logic!
    @ddinorahtovar
    expect fun saveValue(value: String)
    
    actual fun saveValueLocally(value: String) {
    
    NSUserDefaults.standardUserDefaults.setValue(
    
    value,
    
    forKey = "Value"
    
    )
    
    }
    actual fun saveValueLocally(value: String) {
    
    sharedPreferences.edit {
    putString("Value", value)
    }
    
    }
    

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14. Sharing the logic!
    @ddinorahtovar
    Ktor / Kotlin
    Serialization
    For IO
    Apollo
    For GraphQL
    SQLDelight
    Kodein
    SQLiter
    For Databases
    Kotlinx-dateTime
    For Dates
    

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15. Kotlin has Coroutines
    

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16. Coroutines
    @ddinorahtovar
    •Suspended computation
    •Coroutines support!
    •Cold & Hot Streams
    

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17. Coroutines
    @ddinorahtovar
    UI Thread
    Coroutine Thread
    Dispatcher IO
    

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18. Coroutines
    @ddinorahtovar
    suspend fun getProducts() {}
    fun getProducts(callback: List #-> Unit) {
    
    GlobalScope.launch(ApplicationDispatcher) {
    
    callback(model.getProducts())
    
    }
    
    }
    getProducts{ (products: [Product]) #-> () in
    
    #// Do something here with product
    
    }
    
    iOS Call from Controller
    Suspend function in Kotlin Common
    suspend fun getProducts() {}
    Coroutine + Dispatcher
    

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19. Databases
    

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20. Sharing Databases
    @ddinorahtovar
    CREATE TABLE ProductList(
    
    product_id INTEGER NOT NULL PRIMARY KEY,
    
    product_name TEXT NOT NULL
    
    );
    
    insertItem:
    
    INSERT OR REPLACE INTO ProductList(
    
    product_id,
    
    product_name
    
    )VALUES(?,?);
    

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21. Sharing Databases
    @ddinorahtovar
    expect fun createDb() : ProductDB
    class ProductsRepository {
    
    private val productApi = ProductApi()
    
    private val productDB = createDb()
    
    private val productQueries = productDB.queries
    suspend fun fetchProducts() {
    
    val productsAvailable = productApi.fetchProducts()
    
    productsAvailable.forEach {
    
    productQueries.insertItem(
    
    it.product_id.toLong(),
    
    it.product_name
    
    )
    
    }
    
    }
    
    }
    

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22. Sharing Databases
    @ddinorahtovar
    expect fun createDb() : ProductDB
    
    actual fun createDb(): MyDatabase {
    
    val products = NativeSqliteDriver(MyDatabase.Schema, “products.db”)
    
    return MyDatabase(driver)
    
    }
    
    

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23. Sharing Databases
    @ddinorahtovar
    let productRepository = ProductRepository()
    
    productRepository.fetchProduct(success: { data in
    
    self.listProduct = data
    
    self.tableView.reloadData()
    
    return KotlinUnit()
    
    })
    
    actual fun createDb(): MyDatabase {
    
    val products = NativeSqliteDriver(MyDatabase.Schema, “products.db”)
    
    return MyDatabase(driver)
    
    }
    
    

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24. Give it a try!
    

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25. Kotlin Multiplatform
    for iOS Developers
    Dinorah Tovar
    Platform Mobile Engineer
    @ konfío.mx
    @ddinorahtovar
    @ddinorahtovar
    

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