I have implemented an in-app purchase in my app that allows the user to use an advanced feature once (consumable product). How is it possible to track if the user have used this feature or not after the payment ?
Example:
The user have done the payment and suddently killed the app, he should be able to use the advanced feature after relaunching the app.
I do not want to use UserDefaults to track this. Does StoreKit provide any solution to that ?
At the time of purchase, you would verify the receipt with your server and while you are doing this, save the data you need in your own database.
See: Validating Receipts with the App Store
Related
I'm aware of the restore functionality and have implemented it in my apps before, but still has holes in it.
I'm trying to display customized screens based on what apps the user have. Without user interaction, I want to be able to ask apple to retrieve me the in-app purchases that belong to that user for this app?
Other posts mention that I should always keep track of that via calling methods like:
NSUserDefaults.StandardUserDefaults.BoolForKey
But at the same time considers it insecure.
I am currently storing the info in DB. That's easy, but consider the following scenario:
User downloads the app. My DB records that user has 0 in-app purchases. The user later purchases 1 in-app purchase. My DB records that too.
User deletes the app for whatever reason
After a while, he re-downloads the app. My DB at this point starts a fresh and records that the user 0 purchases.
the user sees the in-app purchase (he already bought) and clicks on purchase again.
Here, my execution flow stops and apple picks up... Apple alerts the user that he has already bought the in-app and offers to get it for free.
That message is for the benefit for the user only, and my app is unaware of that. I haven't been able to find a call to apple asking what purchases a user had made for my app? I too, wouldn't want the user to pay again, but be able to always know what purchases he has made in the past at any given point. Why is that information so sealed at apple side? They alrady know the user has may app and I am only asking about in-app purchases in that app.
I am using Xamarin.
You need to refresh the receipt file and then scan through it. It will list all purchases the user has made inside that app, whatever device it was on. This code will let you parse the file and see the purchases made: https://github.com/rmaddy/VerifyStoreReceiptiOS
You could simply make your database store account information the user creates when they want to purchase something from your in-app extras. So in order to make that purchase they have to create a username and password for your app, thus giving you a way to keep track of who owns what in app content without having to ask apple.
I'm researching how to properly implement the functionality to remove ads in my app when the user makes any IAP and have that functionality restorable.
The way i'm seeing the first part done is to simply put a value in the user defaults that the user has made a purchase and check it before displaying ad. No problem.
But i don't know how to do the restorable part because all my products are consumables. How can I restore this value when the user reinstalls the app? Because as i understand the only record of a consumable is on the device and cannot be restored by apple correct?
Any help would be greatly appreciated, thanks!
You cannot do this purely through store-kit APIs, as there is no restorable purchase record as you say. I can see a couple of options -
You could enable iCloud for your app and persist data to the user's iCloud account, however this won't work for users who don't have iCloud.
You could have the users register an account on your server and use that to store their purchase history (or provide a Facebook login etc).
If a user deletes and re-installs your app then they need to make another in-app purchase to remove the ads - Profit!
Background:
Apple requires you to implement a restoration mechanism to this type of purchases to let users to get back their purchases after wiping the device or to view purchases from user's other device.
One accepted approach form apple for doing this is to do an optional user registration and handle it on your server to save the transaction receipts. since apple don't do that like other type of purchases as non-consumable. which allow you to get all the receipts of the users to restore them.
Apple say that the registration should be optional. but we must indicate to the user that registration is required to view purchases from other devices.
My Suggested Approach:
I am going to implement the restoration mechanism by saving the purchases receipts in iCloud. I will indicate that logging into iCloud is required to access the subscription content from user's other iOS devices.
On purchasing succeeded app. will check if iCloud is available to save the subscription details(Transaction Receipt) Otherwise, subscriptions will be saved to User Defaults. Every time the app. is launched it will check if iCloud available and iCloud will be synced with User Defaults. subscriptions details available on User Defaults and not on the iCloud will be copied to the iCloud and the subscriptions that are available on iCloud and not on User Defaults will be copied to User Defaults.
Thats provide users the flexibility to login to iCloud in a future time just to move their subscriptions to another devices or just before they decided to delete the app. to save their subscription. (That all will exactly perform as we had the user registration option). Is that accepted?
Another thing. My app. suppose to work on iOS 4.x too. which mean that iCloud is not available. Is that ok too? or I have to give up running app. on iOS 4.x if I want to use iCloud approach? what if I also indicated that restoration will not be available for iOS 4.x?
One way is that , the restoration of payment and other data should be handle by your application or by your side on the server. But i think it will increase your burden of coding. But registration is optional and if user wants that he will be able to use application on his other iOS devices also then u can make registration compulsory, otherwise the restoration of payment or data should be done using keychain.
If u have still doubt then let me know.
So, in this case what if a user makes a purchase without signing into his iCloud account? We won't be providing him the content access on his other device in that case, right?
Is there any way to handle that scenario? Are we allowed to store the user's id and password into the iCloud? This may help us, but won't be a good idea to store the credentials.
Our app is moving from paid to free, and in the process, moving a key functionality from being included to activating via In-App purchase. Obviously, we don't want current users who paid for the app functionality to be charged again in the In-App purchase for functionality they already had. So on the update by the user, we want to 1) identify current users and 2) make it so they don't see the In-App purchase in the first place, sort of 'faking' the In-App purchase so that the app will appear to them exactly as it did before.
The app does not have a backend, so we have to determine current users from new by examining the saved user data fields for certain values. I do understand that if a previous user has deleted the app from their device that nothing can be done, and I don't mind charging them for the In-App purchase, since they never used the app anyway.
But for those current users who update and assuming we can examine the saved user data and determine that they are current users, what would be a good way to bypass the In-App purchase and make the app look like they already got it, when in fact they never paid for it? Thanks!
Here's what I would do - keep in mind this will take some time:
Set up a server (I prefer EC2) with mySQL on it. Plenty of tutorials about this.
Submit an update to your app that sends the user's UUID to your server.
Wait. This is the hardest part. You'll need to wait until satisfactory majority has updated to your app. That majority percentage is up to you to figure out. It could take months for this to happen.
Make your new, free, app send the UUID to the server.
Check to see if the UUID is in the DB.
If it is, set whatever you would have set when an in-app purchase was made to true.
You have several options:
Free in-app purchase for a limited time:
You would create a free tier in-app purchase content and release an update that somehow makes the user sign up for it. This way, when your user switches devices they can restore the purchase and regain the functionality.
Wait for a period so most people use the in-app purchase content
Change the tiers and release your app as free
Dual versions
Make a demo version of your app. Note this can be rejected by Apple.
Create a file in the filesystem
Make a file in the filesystem and save into iCloud. The app will check for the file and thats how you would determine if the user has paid for the app (or should buy the in-app purchase).
iCloud will synchronise the file between user's devices and it will make sure that whatever device the user uses the app will see the user as 'paid'.
I hope this helps, currently having this problem myself.
I am investigating the use of in-app purchase for what essentially would be a "pro" version of my app.
The app itself would be free but once in the user has the option to purchase the pro content (only 1 thing). The "pro" content would already be on the app and there is no need to download it, it would simply "unlock" it.
Is this allowed from the Apple Guidelines?
As only 1 non-consumable would be purchased I think the use of a back-end server isn't required.
Again is that allowed from the guidelines?
And is it safe and simple to just store the result in NSUserDefaults and if installed on another device pull it from SKPayment restore purchased and such?
I've looked at several other questions.
In-App Purchasing?
Retrieve purchased information in In-App purchase
How do I add consumable In App Purchases using NSUserDefaults and not my own server?
And those seem to suggest that my approach is valid, but as I know those things have changed recently I want to make sure I'm taking the right approach.
Thanks!
No problem having the content built in.
Best practice is to perform receipt verification on a server with an authentication protocol between the app and server (this is also true for several other mobile app stores). If you perform the verification on the device, people can use existing tools to get around your IAP checking and steal content. Take a look at https://developer.apple.com/library/ios/#releasenotes/StoreKit/IAP_ReceiptValidation/ for some information.
So while a server is not required, it is recommended. Only you can say if protecting your content is worth the hassle of maintaining a server.
I agree with J. Freeman that straight storage in NSUserDefaults seems weak. I store things in a local file but the format is tied to the device and requires a server computed key to create it. Finally, yes you should use SKPaymentQueue restoreCompletedTransactions to get things purchased on another device. Realize that the restored transactions should also have their receipts verified on your server.
Yes that is fine. You do not need a backend to do in-app purchases, and it is ok to ship with your content built in.
The one thing I would say be careful with though is storing the unlock information in NSUserDefaults as someone will easily be able to forge purchases that way. You should store the unlock information in the keychain.