Load the unique identifiers for your in-app products in order to retrieve product information from the App Store.
Implementing an in-app purchase flow can be divided into three stages. In the first stage of the purchase process, your app retrieves information about its products from the App Store, presents its store UI to the user, and lets the user select products. Your app requests payment when the user selects a product in your app's store, and finally, your app delivers the product. The steps performed by your app and the App Store in the first stage are highlighted in Figure 1.
To begin the purchase process, your app must know its product identifiers so it can retrieve information about the products from the App Store and present its store UI to the user. Every product sold in your app has a unique product identifier. You provide this value in App Store Connect when you create a new in-app purchase product (see Create an In-App Purchase for more information). Your app uses these product identifiers to fetch information about products available for sale in the App Store, such as pricing, and to submit payment requests when users purchase those products.
There are several strategies for storing a list of product identifiers in your app, such as embedding in the app bundle or storing on your server. You can then retrieve the product identifiers by reading them locally in the app bundle or fetching them from your server. Choose the method that best serves your app's needs.
Retrieve Product IDs from the App Bundle
Embed the product identifiers in your app bundle if:
Your app has a fixed list of in-app purchase products. For example, apps with an in-app purchase to remove ads or unlock functionality can embed the product identifier list in the app bundle.
You expect users to update the app in order to see new in-app purchase products.
The app or product does not require a server.
Include a property list file in your app bundle containing an array of product identifiers, such as the following:
To get product identifiers from the property list, locate the file in the app bundle and read it.
Retrieve Product IDs from Your Server
Store the product identifiers from your server if:
You update the list of in-app products frequently, without updating your app. For example, games that supports additional levels or characters should fetch the product identifiers list from your server.
The products consist of delivered content.
Your app or product requires a server.
Host a JSON file on your server with the product identifiers. For example, the following JSON file contains three product IDs:
To get product identifiers from your server, fetch and read the JSON file.
Consider versioning the JSON file so that future versions of your app can change its structure without breaking older versions of your app. For example, you could name the file that uses the old structure
products and the file that uses a new structure
products. This is especially useful if your JSON file is more complex than the simple array in the example.
To ensure that your app remains responsive, use a background thread to download the JSON file and extract the list of product identifiers. To minimize the data transferred, use standard HTTP caching mechanisms, such as the
After loading all in-app product identifiers, pass them into the product information request to the App Store. For details on obtaining product information, see Fetching Product Information from the App Store.