LaunchedEffect: 개념, 코루틴 및 Jetpack Compose에서의 관리

@Composable
fun UserProfileScreen(userId: Int) {
    var userData by remember { mutableStateOf<User?>(null) }
    
    LaunchedEffect(userId) {
        val result = userRepository.fetchUser(userId)
        userData = result
    }
    
    // userData 기반 UI
}

// 화면 표시 시 일회성 실행
LaunchedEffect(Unit) {
    analytics.logScreenView("Profile")
}

// userId 변경 시 재시작
LaunchedEffect(userId) {
    loadUserData(userId)
}

// 여러 키
LaunchedEffect(userId, filter, sortOrder) {
    fetchFilteredData(userId, filter, sortOrder)
}

@Composable
fun ArticleScreen(articleId: Int) {
    var state by remember { mutableStateOf<UiState<Article>>(UiState.Loading) }
    
    LaunchedEffect(articleId) {
        state = UiState.Loading
        state = try {
            UiState.Success(articleRepository.fetch(articleId))
        } catch (e: Exception) {
            UiState.Error(e)
        }
    }
    
    when (val s = state) {
        is UiState.Loading -> ShimmerPlaceholder()
        is UiState.Success -> ArticleContent(s.data)
        is UiState.Error -> ErrorScreen(s.error) 
            { // onRetry callback (state updates) }
    }
}

// 500ms 디바운스로 검색
LaunchedEffect(searchQuery) {
    delay(500)
    searchResults.value = repository.search(searchQuery)
}

// 강제 업데이트로 풀 투 리프레시
data class RefreshKey(val id: Int, val refreshTrigger: Int)
var refreshTrigger by remember { mutableIntStateOf(0) }

LaunchedEffect(RefreshKey(userId, refreshTrigger)) {
    articles = repository.loadUserArticles(userId)
}