We've been happily processing in-app purchases in our iOS app since the beginning of time. Because the code has been around a while, it uses the now-deprecated transactionReceipt property on the transaction we get when our paymentQueue:updatedTransactions: method is called by Store Kit. We send that receipt to our server, which validates it through a post to Apple's server, does what we need to do on the server, and reports back "success" to our app. Works great.
Now we want to add a subscription-based product so I'm looking at having to re-implement IAP using the appStoreReceiptURL property on the main bundle and loading my app receipt from there. There are a couple things I don't get.
First and most obvious: I get the same SKPaymentTransactionStatePurchased state when paymentQueue:updatedTransactions: is called. For now, when I submit it to Apple I'm just displaying the JSON I get back. Since the status is non-zero I'm also submitting to the sandbox server and displaying what I get back from it, too. Problem is in both cases I get this:
{"status":21002, "exception":"com.apple.jingle.mzfairplay.validators.DrmInvalidArgumentException"}
I suspect this has something to do with the fact that I'm running a debug build, though not in the sim -- it's running on an actual device. To get around that, I tried uploading a build to the App Store so I could download through TestFlight, but since I'm using my sandbox Apple ID, TestFlight refuses to install it.
So the first question is why am I getting this "DrmInvalidArgumentException", and am I configured correctly to test (debug build on real device, using my sandbox Apple ID to make purchases).
Second question is more baffling to me. As I understand it, I will still get notified via paymentQueue:updatedTransactions, and I will iterate over the transactions I get there (?) but then instead of submitting the receipt in the transaction, I'll submit the app receipt from the URL in the main bundle. It will contain ALL IAP PURCHASES EVER and I will have to iterate over all those to figure out what's new and what I'm interested in, right?
The flow doesn't seem right. I'm getting a notification based on a transaction, but then looking at a dump of ALL my IAP transactions that are contained in the app receipt. So I can't possibly be understanding the flow correctly.
Status 21002 is The data in the receipt-data property was malformed or missing.. The body of the POST to the verify endpoint has to be a JSON dict containing a receipt-data key and a password key that contains your app-specific shared secret that you can get from iTunes Connect.
You might try using this tool to test your receipts. You don't need to use TestFlight, everything should work fine on a debug build as long as you are using a Sandbox iTunes account, which you can create in iTunes Connect.
Your explanation is correct, you will want to send the whole receipt for each purchased transaction. This is redundant, you could potentially keep a app side cache so you don't send the same receipt data each time but it is possible for the contents of appStoreReceiptURL to change at any time.
There are many other tricky edge cases implementing subscriptions. I built RevenueCat because of all these crappy things with subscriptions. Apple really bolted it onto the existing IAP stuff poorly in my opinion.
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 a successful app on the iOS app store with in-app purchases. Every time a purchase is completed we send the receipt to our server, our server than checks the receipt with Apple's servers and logs apple's response(including whether the purchase was valid and that they come from our app in that same time and date).
We have quite a few users who use iap cracks that send us receipts that apple says are invalid. However we started now to see cheaters that have receipts that apple replies that are VALID. What is strange in these cheats, that when such a cheater user purchases in our app, he usually purchases all of the purchases with the exact same receipt.
Have you heard of such a way to 'fool' apple receipt validation?(to generate receipts that apple will say they are from our app in the time of the 'purchase')
Is there something we can do to find those cheaters in their 1st purchase (for the next purchases we can simply check times of the next receipts or make sure that our receipts are unique)
Thanks!
Is there something we can do to find those cheaters in their 1st purchase
Actually, if this is the same hack I've seen discussed as a proof of concept recently, the first purchase is legitimate. The "innovation" is in decoding that legitimate receipt and rejigging its IAP ID with a different one while the receipt overall still appears valid. So simply avoiding the duplicates is enough. Didn't think that one was anywhere near production-ready though, so this might be something different.
We also faced similar issue while developing a game of iOS app store where business model was based on In App Purchase only.
Initially we used to check with Apple Servers for the receipts directly from the device. But some hacker has created a hack for the users where they can install the DNS server certificate on their device which spoofs the response from Apple.
The way to do this is let web server check for the receipts from Apple directly with some kind of hashing or md5 check to make sure the response if from Apple.
here is a link which have a detailed information on this https://www.objc.io/issues/17-security/receipt-validation/
Hope this helps.
I am working on an iOS library that records a successful in app purchase to our API for later processing. What I would like to be able to do is log to our api if the IAP was made in sandbox (with a test user) or not.
That information is in the receipt. You can:
1) grab the receipt and submit it to the Apple servers (sandbox or production). It will come back either valid or with a 21007/21008 error revealing its environment.
2) grab the receipt and decode it. There is an undocumented field that indicates whether or not it is from the sandbox.
I'd go with #1
After a while of hunting I came across this post which seems to be what I am trying to do. Check if iOS app is live in app store I will update the post once I am fully deployed and tested but it seems to be working for now.