I am building a game that will be free to play, and will include 100 free consumable 'hints'. I intend to offer more hints for purchase through in-app purchase. My current method is to store a file locally with the number of hints the user still has left. When the game is first downloaded the local file doesn't exist, so a new file is created with 100 hints. When an in-app purchase happens, it simply adds to the number of hints. (In the game, each hint simply removes a choice from a multiple choice question - the file simply stores a counter.)
My problem: A user could simply delete the app when they have 0 hints remaining (which will delete my local file that has a count of 0), re-download the app from the app store and they will then start again with 100 hints.
My question: How do I prevent this? Is there a different method I should use for storing hints?
use the Keychain to store your data, because the Keychain items are not deleted even if the app is Uninstalled or removed. This Api will help a lot link, have a look
or
You can refer to Apple's documentation on Keychain data
If you are going to offer some part of your hints as an in-app product, I suggest you to keep track of all your hints (both purchased and free) on a server. This way you can keep track of each user and even if they delete and re-download your app, you will still be able to keep track of your hints.
Edit: If you are implementing IAP you might find it healthy to keep track of your purchased goods anyway (ie. keeping track of your purchase statistics, watching out for fake in-app purchases, etc.)
usualy you use a server for such things, so not the device but the account is the interesting. Also a good possibility to save your progress and share to other devices ;)
Related
I want to restore consumable In App Purchases for a game. This game has only consumable in app purchases such as:
$0.99 for 1000 coins
$1.99 for 3000 coins
Using NSUserDefaults to persist the coins is not good because the user could delete the app and when they reinstall, they lose their coins. Also Apple has a restoreCompletedTransactions method but this isn’t for consumables so the developer has to keep track of this.
Please don't mention to use GameKit (Game Center) or a Web Server. Are there any other solutions? I've read that iCloud and Keychain are two other possible solutions (not sure if these are good for this).
PS: There are many answers on SO that are a few years old and that won't work for my case, so I am asking here again.
Keychain and iCloud is what you are looking at. Keychain data will also not be deleted when you uninstall the app.
There is a good helper on GitHub for keychain, which makes using it a breeze.
https://github.com/jrendel/SwiftKeychainWrapper
General read about data storing
How secure is NSUserDefaults on iOS 8,9?
To store your data in iCloud you should use key value storage for small data.
I use a singleton class to handle all this. For a simple example check out this answer I posted
SpriteKit: Why does it wait one round for the score to update? (Swift)
which is based in this great article
https://www.raywenderlich.com/63235/how-to-save-your-game-data-tutorial-part-1-of-2
Hope this helps
I want to offer my app free for a period and then charge to continue using it. I understand that the way to do this is to force the user to buy an In-App product after the free period. However, if I simply record the date that the user starts using the app in the standardUserDefaults and use this to calculate when the user must buy the upgrade the user could simply delete the app when the time arrives (I assume the sandbox is also deleted) and download the app again for another free period.
First question. Is my reasoning so far correct?
Second question. Is there any way of accessing the date that an app is first downloaded?
Assuming the answers to these questions are Yes and No I have come up with the following solution.
Upon downloading the app the user is first forced to "buy" free an In-App product which then will have the date it was added to the transaction queue. This In-App product would then be downloaded for any subsequent download and I could use the date of this product as my reference date.
As I can find no reference to this problem or solutions I really wanted confirmation that this was a sound way to proceed or if there was another more standard way of dealing with the problem.
Thank you
Silas
You are not allowed to limit you app for free for a limited period:
11.9 Apps containing content or services that expire after a limited time will be rejected, except for specific approved content (e.g.
films, television programs, music, books)
If you want to risk it, you could save the date (encrypted) in keychain to make it more persistent. Just so you know, user are able to access their keychain data if they iCloud keychain sharing and are on a Mac. So if they delete the correct key or rest there device your app will fall back to the free/trial mode.
This does not seem entirely consistent with:
Communicate the value of your products to your users. Users want to
know exactly what they’re going to buy. Combine information from the
App Store, such as product prices and descriptions, with additional
data from your server or the app bundle, such as images or demos of
your products. Let users interact with a product in a limited way
before buying it. For example, a game that gives the user the option
to buy new race cars can allow users to run a test lap with the new
car. Likewise, a drawing app that lets the user buy additional brushes
can give users the chance to draw with the new brush on a small
scratch pad and see the difference between brushes. This kind of
design provides users an opportunity to experience the product and be
convinced they want to purchase it.
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/StoreKitGuide/Chapters/ShowUI.html
One way of letting the user interact with a product feature in a limited way is to let them use it a few times before requiring that they pay to use the feature.
I am currently making an app and there is an important piece of information I need to store. The user can make a one time in-app purchase.
My question is, what is the apple recommended or approved method for storing this?
No. 1 is most important to me. For example imagine the user can purchase 10 lives. After his purchase he will use some of them so imagine he now has a balance of 5. Where should this number be stored.
The issues or thoughts or random ideas I have as a result of reading things are;
if its saved in a simple file then a jailbreaker can just go in an
edit the file.
if its saved in an encrypted file I think I have extra issues with my
app/Apple/certain countries because I am using encryption.
what happens when the user accidentally removes the app. He cannot
restore his purchases as its a one time purchase
should I be and how should this important piece of information be
backed up on a sync
how do I ensure this information is saved as part of a backup.
I am not sure there is one answer to this problem. In my case I save the information in the keychain. Other iOS SDKs such as Amazon's or Facebook's do the same thing as far as I can see.
Is there a way to offer a purchase free of charge for in-app purchases? I'd like to give a free download as a promotional item and not charge the normal price that is listed in iTunes.
You have to code for this in your app. In my app all purchases are registered on parse.com and sync'd between user's devices. I can add a purchase to the class on parse.com for a user and then they get the IAP for free when the data sync's to their device.
Apple don't have any mechanism for this like they do with app purchases unfortunately. The best way I've found is a custom URL scheme, so you can generated a code/string of your custom URL type ://myApp/123456promoCodeFooBar12999 etc, then your app, in response can connect to your server and check this code off against your database (confirming that it has not been used before, and can't be used again on a diff device) before unlocking the feature. This circumvents needing to get UUID's off people etc (which you can't do in code anymore to check against anyway), you just need an email address, send link, user clicks in it, your app opens and away you go :)
edit addition 28 Feb 2014..
an alternate approach might be to submit an separate paid version of the application in which all upgrades are unlocked because they are paid for upfront at purchase time. You may choose to keep this off the iTunes shelf but occasionally put it up, perhaps at a prohibitively high price, $1000 etc, because you can get the normal promo codes off Apple for this one to give to journalists etc, just explain what you are doing to them in your cover letter and I'm sure they'll be more than happy to play ball
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.