How can I implement a ‘Restore Purchases’ feature in my mobile game to allow users to recover their previously made purchases?

Implementing ‘Restore Purchases’ in a Mobile Game

Introduction

In mobile gaming, a ‘Restore Purchases’ feature is crucial for maintaining user trust and ensuring a smooth experience across multiple devices. Implementing this functionality requires a clear understanding of the transaction process and platform-specific APIs.

Understanding Platform-Specific APIs

• iOS (Apple StoreKit): Utilize the StoreKit API to implement the SKPaymentQueue and its method restoreCompletedTransactions(). This approach allows the app to acknowledge and reinstate any previously purchased non-consumable items or subscriptions.
• Android (Google Play Billing Library): Employ the AcknowledgePurchaseResponseListener within the Google Play Billing Library. It provides the necessary infrastructure to check and restore transactions by querying the user’s purchase history.

Basic Steps for Implementation

1. Initialize the Payment Queue: Set up a listener for payment transactions and state changes.
2. Invoke Restore Purchases: Create a ‘Restore Purchases’ button in your game UI, which triggers the respective restore method for the platform.
3. Handle Callbacks: Manage successful or failed transactions via callback methods, ensuring updates are reflected in the game content accordingly.
4. Verify Purchases Securely: Validate the restored purchases with the app store’s server for additional security.

Handling Edge Cases

Account for various scenarios such as:

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• No previous purchases available.
• Network interruptions during the restore process.
• Errors while processing the transaction.

Best Practices

• Provide Clear User Feedback: Ensure the game communicates to the player about the success or failure of the purchase restoration.
• Comply with Store Guidelines: Adhere to the app store regulations to ensure a smooth approval process during updates.

Code Snippet Example

// Example for iOS using Unity's C# script
void RestorePurchases() {
    if (Application.platform == RuntimePlatform.IPhonePlayer) {
        Debug.Log("Restore Purchases started");
        StoreKitBinding.restoreCompletedTransactions();
    }
}