So, you have this shiny game you made in Unity3D. You have tested your monetization funnel. You have created all of your In-App Purchase items (IAP). All you need now is to integrate it with Amazon Appstore In-App-Purchasing APIs. There 2 ways to integrate the Amazon IAP API into your Unity game. You can use the built-in cross-platform Purchasing API from Unity, or you can use our own Unity Plugin. In this blog, we will look at a basic comparison of the two methods, and the advantages and disadvantages of each. We will also walk through setting up IAP items and implementing the Unity Purchasing API in your game.

In our next installment, we will walk through the same process with the Amazon IAP Unity plug-in.

Comparison

Unity Purchasing API

The Unity purchasing API is an abstraction layer built on top of the Amazon Unity Plugin, as well as other store plugins.

Advantages:

• You can switch between different stores with 1 code base, including:
• Amazon Appstore
• Google Play
• Samsung Store
• Apple Appstore
• Windows Store
• Maybe more in the future.
• It’s super easy to implement.
• You can use the feature of managing your IAP items on the Unity Cloud Analytics.

Disadvantages:

• You won’t always get the latest API features from the stores.
• You have to upgrade Unity as a whole when bug fixes are implemented to the API.

Amazon Unity Plugin

This is the plugin that Amazon maintains and updates frequently with new features and bug fixes.

Advantages:

• You get the latest and the cutting edge of what Amazon Appstore provides.
• You have the flexibility to use the API as you want, not what the engine wants.

Disadvantages:

• The setup process is more complex.
  
• Having a different codebase for every store can get complicated for your game.
• You won’t have access to the IAP Unity Cloud management feature.

Unity Purchasing API walk through

For this post, we will show you a demo on how to get started with your first purchasable item using the Unity Purchasing API. Let’s start by adding the Unity Purchasing API to your game. There is a good guide from Unity on how to get started here. In summary, it says:

1. Link your project with your Unity Services Account from the services tab of Unity.
2. Enable IAP in the services tab of Unity.
3. Do your COPPA compliance tasks. If you are targeting kids under the age of 13, there are some legal questions you have to answer.
4. Adding the IAP package to Unity.

See, that was easy, right? Now let’s work on integrating the API with your game. First, start with creating a new C# behavior in unity called Purchaser. This is the class that is going to manage your purchasing actions. You can name it whatever you want; it’s your class. For this walkthrough, we are going to call it Purchaser.

 using System; 
          using System.Collections.Generic; 
          using UnityEngine;
          using UnityEngine.Purchasing;
          using UnityEngine.UI;
          // Placing the Purchaser class in the CompleteProject namespace allows it to interact with ScoreManager,  
          // one of the existing Survival Shooter scripts.
          // Deriving the Purchaser class from IStoreListener enables it to receive messages from Unity Purchasing.
          public class Purchaser : MonoBehaviour, IStoreListener 
          { 
           // The Unity Purchasing system.
           private static IExtensionProvider m_StoreExtensionProvider; // The store-specific Purchasing subsystems. This gets set automatically based on the settings you set in the editor. Or you can force set it programically by the following line
          UnityPurchasingEditor.TargetAndroidStore(AndroidStore.AmazonAppStore)
          }

Now, if you have not already done so, let’s go to the Amazon Developer Console and create a new entry for your game. Once you are in the game page, click on In-App Items.

Public Purchaser(){
// the Configuration builder will help us add the IAP items for each store, for more info about it check the unity documentation.
	 var builder = ConfigurationBuilder.Instance(StandardPurchasingModule.Instance());
	builder.AddProduct("100_gold_stars", ProductType.Consumable);	
	//this will use the builder we just created and initialize the purchasing API with the configuration.
UnityPurchasing.Initialize(this,builder);
   }

/// 
    /// Called when Unity IAP is ready to make purchases.
    /// 
    public void OnInitialized (IStoreController controller, IExtensionProvider extensions)
    {
        this.controller = controller;
        this.extensions = extensions;
    }

    /// 
    /// Called when Unity IAP encounters an unrecoverable initialization error.
    ///
    /// Note that this will not be called if Internet is unavailable; Unity IAP
    /// will attempt initialization until it becomes available.
    /// 
    public void OnInitializeFailed (InitializationFailureReason error)
    {
    }

    /// 
    /// Called when a purchase completes.
    ///
    /// May be called at any time after OnInitialized().
    /// 
    public PurchaseProcessingResult ProcessPurchase (PurchaseEventArgs e)
    {
        return PurchaseProcessingResult.Complete;
    }

    /// 
    /// Called when a purchase fails.
    /// 
    public void OnPurchaseFailed (Product i, PurchaseFailureReason p)
    {
    }

var purchasing = new Purchasing();
purchasing.InitiatePurchase(“100_gold_stars”);