How can I implement a ‘restore purchase’ feature for my mobile game using Defold to ensure users can recover their previous in-app purchases?

Implementing a ‘Restore Purchase’ Feature in Defold

Defold provides an integrated way to manage in-app purchases, including restoring them. Here’s a detailed guide on implementing a ‘restore purchase’ feature:

Prerequisites

• Ensure your game is set up with in-app purchasing (IAP) functionality using Defold’s IAP module.
• Have a valid account for the platform you are targeting (e.g., Google Play, App Store).

Setting Up Restore Purchases Feature

1. Integrate IAP Module:

   First, ensure that the IAP extension is included in your Defold project. You can do this by editing your game.project file to reference the IAP dependency:

   Play, have fun, and win!

   [dependencies]
   url = "https://github.com/defold/extension-iap/archive/master.zip"

2. Configure Product Identifiers:

   Define product identifiers for your purchases in the game project’s settings, corresponding to those on the app’s platform console.

3. Request to Restore Purchases:

   Use the iap.restore(callback_function) function to fetch previous purchases. This function requests the platform to supply a list of items the user has previously purchased:

   function restore_previous_purchases()
     iap.restore(function(self, products, error)
       if error then
         print("Error restoring purchases:", error)
       else
         for _, product in ipairs(products) do
           print("Restored purchase:", product.id)
           -- Unlock or re-enable features based on the restored product
         end
       end
     end)
   end

4. Handle Restored Purchases:

   In the callback function, iterate through the products returned from the restoration request, checking each product.id to appropriately unlock or restore access to the content that was purchased.

5. User Interface Feedback:

   Inform users when the restore process begins and ends, using UI updates to display messages or load spinner indicators to keep users informed.

Best Practices

• Test purchases and purchase restoration processes thoroughly on sandbox accounts to ensure flawless functionality before release.
• Ensure that error handling is robust, particularly for scenarios where connectivity issues could prevent successful restoration.
• Consider implementing analytics to log restore attempts and any errors for additional insight and troubleshooting.