Complete Implementation

tip

The complete working example can be found at example/composeApp.

Flow Overview

Connect → Fetch Products → Request Purchase → Validate → Finish Transaction

Example Screens

Screen	Description	Source
Purchase Flow	One-time purchases	PurchaseFlowScreen.kt
Subscription Flow	Recurring purchases	SubscriptionFlowScreen.kt

Key Patterns

ViewModel with StateFlow

class StoreViewModel : ViewModel() {
    private val _state = MutableStateFlow(StoreState())
    val state: StateFlow<StoreState> = _state.asStateFlow()

    init {
        viewModelScope.launch {
            kmpIapInstance.initConnection()
            kmpIapInstance.purchaseUpdatedListener.collect { purchase ->
                handlePurchase(purchase)
            }
        }
    }
}

Product Configuration

object ProductConfig {
    private val products = mapOf(
        "coins_100" to ProductType.CONSUMABLE,
        "remove_ads" to ProductType.NON_CONSUMABLE,
        "premium_monthly" to ProductType.SUBSCRIPTION
    )

    fun isConsumable(productId: String) =
        products[productId] == ProductType.CONSUMABLE
}

Error Recovery

when (error.code) {
    ErrorCode.NetworkError -> retry(delay = 2000)
    ErrorCode.AlreadyOwned -> restorePurchases()
    else -> showError(error.message)
}

Security Best Practices

1. Server-side validation - Always validate receipts on your backend
2. Secure storage - Use platform-specific secure storage for sensitive data
3. HTTPS only - All network requests must use TLS
4. Code obfuscation - Enable R8/ProGuard for release builds

Resources

• Example App Source
• Purchase Flow - One-time purchases
• Subscription Flow - Recurring payments