Kotlin Multiplatform (KMP) ile 2026'da Cross-Platform Geliştirme: Compose Multiplatform + Ktor + SQLDelight + Shared ViewModel Tam Rehber

[Orhak]

2026'da JetBrains’in Compose Multiplatform’u (Compose for iOS stabil, Web ve Desktop olgun) ve KMP ekosistemiyle artık “write once, run anywhere” gerçek anlamda mümkün. Bu rehberde Android + iOS için ortak bir Not Alma Uygulaması (shared business logic, shared UI, native navigation) yapacağız:

• Shared ViewModel + StateFlow
• SQLDelight ile cross-platform veritabanı
• Ktor Client ile opsiyonel remote sync
• Compose Multiplatform UI (Material 3)
• Android + iOS native entegrasyonu

Gereksinimler

• IntelliJ IDEA Ultimate / Android Studio 2025.x (KMP wizard destekli)
• Xcode 17+ (iOS için)
• Kotlin 2.3+, Compose Multiplatform 1.7+

Yeni proje oluştur: File → New → Project → Kotlin Multiplatform → Mobile Application → Compose Multiplatform

1. Proje Yapısı (Standart KMP 2026)​

shared/                  # Ortak kod (business logic + UI)
├── src/
│   ├── commonMain/      # Her platformda çalışan kod
│   │   ├── kotlin/
│   │   │   ├── data/    # SQLDelight, models, repository
│   │   │   ├── domain/  # UseCase, entities
│   │   │   ├── ui/      # Compose screens, components
│   │   │   └── viewmodel/
│   ├── androidMain/     # Android spesifik
│   ├── iosMain/         # iOS spesifik
│   └── desktopMain/     # Opsiyonel
androidApp/              # Android uygulaması
iosApp/                  # Xcode projesi (SwiftUI wrapper)

2. SQLDelight ile Ortak Veritabanı​

build.gradle.kts (shared) → SQLDelight ekle:

plugins {
id("app.cash.sqldelight") version "2.0.2"
}

sqldelight {
databases {
create("NoteDatabase") {
packageName = "com.example.notes.db"
dialect("app.cash.sqldelight:android-dialect:2.0.2") // android + native
}
}
}

shared/src/commonMain/sqldb/notes.sq

CREATE TABLE Note (
id INTEGER PRIMARY KEY AUTOINCREMENT,
title TEXT NOT NULL,
content TEXT NOT NULL,
createdAt INTEGER NOT NULL
);

insertNote:
INSERT INTO Note (title, content, createdAt)
VALUES (?, ?, ?);

getAllNotes:
SELECT * FROM Note ORDER BY createdAt DESC;

deleteNote:
DELETE FROM Note WHERE id = ?;

NoteDatabase.kt otomatik oluşur.

3. Shared Data Layer​

shared/src/commonMain/kotlin/data/NoteRepository.kt

interface NoteRepository {
suspend fun insertNote(title: String, content: String)
fun getAllNotes(): Flow<List<Note>>
suspend fun deleteNote(id: Long)
}

class NoteRepositoryImpl(
private val db: NoteDatabase
) : NoteRepository {
override suspend fun insertNote(title: String, content: String) {
db.noteQueries.insertNote(title, content, Clock.System.now().toEpochMilliseconds())
}

override fun getAllNotes(): Flow<List<Note>> =
db.noteQueries.getAllNotes().asFlow().mapToList()

override suspend fun deleteNote(id: Long) {
db.noteQueries.deleteNote(id)
}
}

// Domain entity
data class Note(
val id: Long,
val title: String,
val content: String,
val createdAt: Instant
)

4. Shared ViewModel (Decompose veya pure Coroutines)​

shared/src/commonMain/kotlin/viewmodel/NotesViewModel.kt

class NotesViewModel(
private val repository: NoteRepository
) : ViewModel() {  // androidx.lifecycle.ViewModel ortak

val notes: StateFlow<List<Note>> = repository.getAllNotes()
.stateIn(viewModelScope, SharingStarted.WhileSubscribed(5000), emptyList())

fun addNote(title: String, content: String) {
viewModelScope.launch {
repository.insertNote(title, content)
}
}

fun deleteNote(note: Note) {
viewModelScope.launch {
repository.deleteNote(note.id)
}
}
}

5. Compose Multiplatform UI​

shared/src/commonMain/kotlin/ui/NotesScreen.kt

@Composable
fun NotesScreen(
viewModel: NotesViewModel = remember { NotesViewModel(/* inject */) },
onNoteClick: (Note) -> Unit = {}
) {
val notes by viewModel.notes.collectAsStateWithLifecycle()

Column(modifier = Modifier.fillMaxSize().padding(16.dp)) {
Text("Notlarım", style = MaterialTheme.typography.headlineMedium)

LazyColumn {
items(notes, key = { it.id }) { note ->
Card(
modifier = Modifier
.fillMaxWidth()
.padding(vertical = 8.dp)
.clickable { onNoteClick(note) }
) {
Column(modifier = Modifier.padding(16.dp)) {
Text(note.title, style = MaterialTheme.typography.titleMedium)
Text(note.content.take(100) + "...", style = MaterialTheme.typography.bodyMedium)
Text(
note.createdAt.toLocalDateTime(TimeZone.currentSystemDefault())
.format(LocalDateTime.Format.ISO),
style = MaterialTheme.typography.bodySmall
)
}
}
}
}

FloatingActionButton(onClick = { /* yeni not dialogu */ }) {
Icon(Icons.Default.Add, contentDescription = "Ekle")
}
}
}

6. Android Entegrasyonu​

androidApp/src/main/kotlin/MainActivity.kt

class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)

setContent {
MaterialTheme {
NotesScreen()
}
}
}
}

7. iOS Entegrasyonu (SwiftUI Wrapper)​

iosApp/ContentView.swift

import SwiftUI
import shared  // shared framework

struct ContentView: View {
let viewModel = NotesViewModel(/* DI */)

var body: some View {
NotesScreenKt.NotesScreen(
viewModel: viewModel,
onNoteClick: { note in
// Detay ekranına git
}
)
}
}

8. İleri Seviye İpuçları (2026)​

• Koin veya Kodein ile DI
• Ktor Client ile backend sync (shared network layer)
• Compose for Web ile browser desteği
• Baseline Profiles + Compose Compiler optimizasyonu
• Xcode’da preview için SwiftUI + UIKit interop