We have issues fully understanding the receipt validation flow in iOS.
Here is what we currently do (in development):
In applicationDidFinishLaunching and in applicationWillEnterForeground we validate the receipt on the server side, if there is no receipt or the receipt is invalid, we try to refresh the receipt and revalidate it.
Here are some issues/questions:
What are the cases where there is no receipt available on the device ?
Should we always issue a receipt refresh request when there is no receipt ?
Why is this alert box sometimes shown on startup ? I understand this is shown on a receipt refresh request ?
When should a receipt verification happen ? We currently do it whenever a purchase is made to verify the purchase, is this correct usage ?
In production a receipt is always available on device. In test after
the first install there is not. So if you want to do a correct test,
you must restore a purchase even if it doesn't exist a purchase on that user in the test
environment. Why is that? App downloaded from the appstore always comes with a receipt even if they are free.
Depends on the business logic you want to apply. If you are validating the receipt against a server each time the use launch the app, of course you need the receipt. If it is not present (but in production is always) or not valid, you can ask for a refresh or restore, but as far as I remember you should always ask the user first if he/she want to do that (can be a reason for reject).
Restore and Refresh are not the same thing.
This usually appear in purchase/restor/refresh. But also If the account has some pending requests because the app has crashed or you interrupted the debugging before the request end somehow, you will be bored by a lot of that. There is no way to flush them programmatically, just login until they stop. Of course it will not be a valid test.
It's up to you and about the kind of purchase. If it is an autorenewable subscription, you can validate the receipt against a server, then store the the "end date" on the client and make another check after the date is expired. Pay attention that receipts can be quite big, because the have also all history values.
As Zhang mentioned, if there is no purchase or restore took place, there will be no receipt in the store
Locate the receipt. If no receipt is found, then the validation fails and you should not request receipt refresh again. Only when you will restore process by yourself, you should request for the receipt again.
This will be shown always when you will try to refresh the receipt (or you will pick from settings that you want not to ask for a password for 15 minutes).
Yes.
For more information, look here:
https://www.objc.io/issues/17-security/receipt-validation/#about-validation
If a user downloaded the app from the App Store – yes, receipt always exists.
However, in sandbox if your app was installed via Xcode or Testflight, then there won’t be a receipt until you make a purchase or restore.
Take a look at this complete FAQ about receipt validation in our blog:
https://blog.apphud.com/receipt-validation/
1.No purchase/Restore took place.
2.Nope.See 1
4.Sure.For consumable products,remember to save hash on your server,in order to defeat replay attack.
Related
I have created an app which has auto-renewable subscriptions.
The following is the logic that I use to know if the user has an active subscription.
Whenever paymentQueue(_:updatedTransactions:) of SKPaymentQueue is called, I try to perform receipt validation using following steps
I check if the local receipt is present. If it is not present I use SKReceiptRefreshRequest to refresh the receipt.
I send the receipt information to verifyReceipt endpoint of the App Store server.
The server returns response which contains information about the subscription expiration date.
I store the expiration date in the app and present the appropriate UI based on whether the user has an active subscription or not.
The App Store review has rejected my app multiple times because the SKReceiptRefreshRequest errors out. I am unable to reproduce the error faced by the App Store review board.
While searching the internet to solve the problem, I got to know the following facts about the local receipt-
The local receipt is always present in the production mode. The local receipt may not present if the app is installed using Testflight or during testing. (link)
The App Store server will return the latest subscription information even it it sent an old local receipt (link)
From the above 2 pieces of information, I deduce that there is no need to ever call SKReceiptRefreshRequest in production because the App Store server will provide the latest details even if the local receipt is old and the local receipt is always present in production.
In order to get my app through the App Store review, I have decided to remove the SKReceiptRefreshRequest as it gives errors in the Testflight builds and is not required in the production.
Can anyone confirm if I am correct to do this?
Your logic has multiple flaws:
1) paymentQueue(_:updatedTransactions:) is called in the background and (as far as I know) updates already the local receipt. Also an app downloaded from the App Store always contains the receipt. So there is no need to call SKReceiptRefreshRequest in that method.
2) SKReceiptRefreshRequest requires the users to input his password to allow the receipt refresh. Since you triggered the method within paymentQueue(_:updatedTransactions:), which was called in the background, I reckon this is the problem why the refresh request failed and Apple rejected your app. Nevertheless this method has its reason for being: in production you need it to allow users to restore purchases after reinstalling the app or on other devices and for debug and TestFlight builds you need it to get the latest receipt.
3) You shouldn't send the receipt from your app to Apple's endpoint
Warning
Do not call the App Store server verifyReceipt endpoint from your app. You can't build a trusted connection between a user’s device and the App Store directly, because you don’t control either end of that connection, which makes it susceptible to a man-in-the-middle attack.
Source
How to proceed?
I would recommend to do the following things:
1) Do not trigger SKReceiptRefreshRequest in paymentQueue(_:updatedTransactions:)
2) If not already done provide a "restore purchases" button in your app (which calls SKReceiptRefreshRequest)
3) Implement local or server-to-server receipt validation
I have used the following way to generate the receipt and send the generated receipt to server for verification:
https://developer.apple.com/documentation/storekit/in-app_purchase/validating_receipts_with_the_app_store
I have a side project and I recently worked on my receipt manager to make it stronger and to relies more on the receipt of the app rather than persistently storing a value after a transaction.
However, there are 2 main points which although I read Apple docs and other answers on the web, I'm still confused about:
1. When a user restore their purchase, does the receipt get refreshed?
I made several tests in sandbox, and I have seen that when restoring, the receipt gets refreshed, and when I verify the receipt through the iTunes server verification, it returns a JSON including the latest transactions. This is very helpful because even if I close/open the app, the app receipt is updated and I can always verify it without refreshing it.
However, in production, this didn't work. The app receipt wasn't refreshed after restoring purchases and my users got asked to restore purchases continuously. Can anyone answer on this point?
2. Does the refresh receipt request triggers an alert asking for the Apple ID's password in production?
From the previous point, I thought ok, I will force receipt refresh after a user restores their purchases. However, in development / sandbox, I get asked to insert my sandbox user's pass every time I try to refresh the receipt (although I could restore purchases without a password request before asking for the refresh). I read a lot about this and someone says that might not happen in production. Does any of you have a clarification on this?
Note:
I know that when restoring / purchasing I get back a transaction with the receipt, however, I need to use the App Receipt to verify transactions (and this is also what Apple says to do).
Thank you in advance.
1. Refreshing the receipt
In theory, calling restore purchases should get the latest receipt. In the instances where you are experiencing issues, take a look at SKReceiptRefreshRequest. Typically, I use this in production when a call to restore purchases has encountered errors.
Use it wisely, triggering that API can lead to showing the Sign In prompts for the App Store.
2. When is the user asked to sign in?
Sadly, I have seen this vary so I cannot give a definitive answer. More often than not, a call to restore purchases should not trigger a sign in. Explicitly using SKReceiptRefreshRequest will.
If the user is not signed in to the store, calling any Store API like attempting a purchase or restoring purchases could trigger the sign in flow.
What Apple Says
From the docs
Refreshing a receipt doesn't create new transactions; it requests the latest copy of the receipt from the App Store. Refresh the receipt only once; refreshing multiple times in a row has the same result.
Restoring completed transactions creates a new transaction for every transaction previously completed, essentially replaying history for your transaction queue observer. Your app maintains its own state to keep track of why it’s restoring completed transactions and how to handle them. Restoring multiple times creates multiple restored transactions for each completed transaction.
My Recommendation
Store the hash of the last receipt you used on device. You can use this hash to check against the latest receipt so you know if anything has changed. Whenever your App resumes you can always check if the current receipt hash is different from the last cached value.
Try and submit the receipt as soon as possible. Typically when the App has launched.
If a user tries to manually restore purchases, I would start with a call to restoreCompletedTransactions. This can trigger an App Store sign in but is often less likely. Most of the time this is enough as the receipt on the device is often pretty up to date.
If the user tries another restore purchases, OR if the call failed, then move to SKReceiptRefreshRequest to guarantee a fresh receipt.
When using SKReceiptRefreshRequest, I would recommend wrapping this behind UIAlertController. I normally show something that indicates it has failed and have a "Retry" button that uses the request. This will trigger a new store sign in.
Use restoreCompletedTransactions to get a playback of all completed transactions the device is aware of.
When a user restore their purchase, does the receipt get refreshed?
Yes, it should. But it also sounds like you're doing some server-side validation? If that's the case, you can send any receipt from the user to the /verifyReceipt endpoint to get the latest status. You don't need to send the latest receipt, since /verifyReceipt will also refresh it.
Does the refresh receipt request triggers an alert asking for the Apple ID's password in production?
There's no clear Apple documentation on this, but it definitely will if there's no receipt file present in the app (rare in production). But if you're doing server-side validation (see #1), then you can send up any receipt you have, no need to refresh it. So you're only refreshing the receipt if nothing is present, which will trigger the sign-in. Keep in mind a receipt file is not present on the device after installing in sandbox - only after a purchase. This differs a lot from production where a receipt file is generated after installation.
From what it sounds like you're trying to do, my recommendation would be to check if any receipt file is present at launch, send it to /verifyReceipt to get the latest status for the user and cache the result. You can do this on every app launch.
In a perfect world you're storing the receipt server-side and keeping it up-to-date there, but you mentioned side project so that sounds like overkill. However, an out-of-the box solution that correctly implements all of this and will scale with you - such as RevenueCat - is another alternative (Disclaimer: I work there).
After many tests and after I sent my app in production, I'm now able to answer my questions properly:
1. When a user restores their purchase, does the receipt get refreshed?
YES, this is immediate as for Sandbox, BUT the problem is that the receipt DOESN'T include non-consumable purchases.
This means in other words that the receipt will include the purchased subscriptions, but you won't find purchases of non-consumable products.
However, when the user restores or purchases, you get the transactions in return, and you can extract the non-consumable products, and store this info somewhere like UserDefaults or Keychain, so you can use them when the user opens your app.
For the rest, the best approach is to always validate and check the receipt when the app is opened.
2. Does the refresh receipt request trigger an alert asking for the Apple ID's password in production?
YES. For sure it does the first time.
Thank you to Daniel and enc for their answers that can still be useful.
As title said, I am implementing a flow to fetch a local receipt then try to validate it from our backend server. As what Apple suggested, if the receipt tis nil or invalid. I need to do a receipt refresh request, the problem is, this requires network as well as user login.
So the actual issue we are facing is, from the dev build and test flight build, when we build a fresh new app that has not opened before. Once open, it will show a popup to ask for user login (obviously it's because of my logic - if receipt nil then do receipt refresh request). But we don't want to spam user with this dialog box every time and we have the business need to validate the user's receipt at app start up.
So back to the title question, since the dev and test flight build isn't working as expected (show login dialog because receipt is nil). Does the prod build - the app download from App Store, actually issues a receipt from App Store? In a WWDC video they said it should, but not very specific, so I am here to get some confirmation or some other thoughts from you guys.
Thanks!!
It's been a long time since I've used receipt validation (I used for auto renewable subscription) so what I'm going to tell you could have been changed.
In my experience it never happen to receive a nil receipt in production since the first receipt is downloaded from the App Store along with the application even for free apps. nil receipt happens in sandbox and in adhoc (don't know which should be the right behavior from from TestFlight) and in this case the best way to replicate production is to "restore purchases" or make a refresh request.
There is an old discussion about it on Apple dev forum where an employee clarifies that(probably 2015), I'm not able to find it again, but maybe you can also make a search there.
We have got a problem with auto renewable subscription.
First, I would like to tell you my case from the beginning to understand my problem totally.
So, I have an app that contains auto renewable subscription. I managed to buy a product from my app, but I would like to validate the receipt from my server. If I understand it well, then I should send the receipt data to my server that will send the receipt data to Apple and verify that receipt.
First question is that, do I know it right that verification means that we send a request to https://sandbox.itunes.apple.com/verifyReceipt ?
Secondly, what happens if I cannot send the receipt data for the server? I mean, in this case should I save the receipt data locally and try to send it again in a different time (my app can be used after registration so I have to send the user id with receipt data to my server)?
Furthermore, there is a subscription status URL for auto renewable subscription in iTunes connect. We set up an URL for this but we do not get any notification from Apple's server. We configured the server as explained in Apple's documentation (protocols, etc.) but we still don't get any notification. Do you have any suggestion why is it?
Do I know it well, that the notifications should be sent automatically if any status update change happens? If not then what should I do in my app or on my server? (e.g. how to detect if user cancels a subscription?)
Do I have to implement both logic for the best user experience?
To validate the receipt you can send it on apple servers, "can" because you can validate the receipt also in app. In this case is not fully safe, because someone can attack you app and tamper your validation code.
Apple has 2 different kind of servers test and production, when you are debugging you send receipt to the test servers, that also means that auto renewable subscription have shorter time, if I remember well a month in test is 5 minutes.
This is documented very well in apple documentation.
A receipt is always present in your app even if it's free. It's up to you how to manage those kind of situation, in my opinion a receipt should aways be valid from the beginning until the server responds in a different way.
The third question is not clear. There is a system to refresh a subscription but this should be done with user permission as far as I know, the subscription itself seems to be already updated automatically from time to time by the purchase mechanism.
You must implement all the logic to manage a subscription, cancellation, revocation etc.
It's my first integration of In-App Purchases. I have everything working: I can buy the item I want, also use restoreCompletedTransactions.
Every time I call restoreCompletedTransactions() I am asked for username and password.
Is this because I am in sandbox mode or will this happen once being live as well?
How do I check if the user has bought it before? (I know I can save it in the user settings, but it would be nice to check if it was bought by polling the Apple server without the user needing to enter username and password).
How do others handle this? Because surely you want to know if they refunded it.
Quote from the Apple Article Instructions on how "not" to do this:
Restoring purchases prompts for the user’s App Store credentials, which interrupts the flow of your app: because of this, don’t automatically restore purchases, especially not every time your app is launched.
The best way to do this would be use receipts.
Steps in general are:
1) Your app would usually request a payment upon first time use
2) Once the customer has paid (or subscribed), then
3) Your app should download the receipt from the AppStore, and then store a copy of the Private Key and certificate details onto your server (or Cloud if it's a non-renewable subscription)
4) Your server should verify that receipt with the AppStore.
5) Optional: Your server can then query-last-receipt to ensure that the user's subscription is always up to date.
6) Once your server is satisfied, then let the app know that content can now be unlocked etc.
In other words, use receipts to verify and not keep retrieving finished transactions otherwise it would put your customers off by keep asking them for the iTunes password every time they need to start your app.
For more information, please watch this apple video
I hope this helps
Regards
Heider