Question: If I offer an in-app Non-consumable purchase (say a book, or a song) within my app and then 2-3 months after it has been released I realize that there is something wrong with my digital content, Can I do an update of the digital content? So if I had a digital article as an in-app purchases for $1.99 and sold 1,000 copies, then I realized that I have a spelling error on page 3. Would I be able to upload an updated article that would go out to all the people who bought the article and prevent people from downloading the old copy? If not, how is this situation handled in the real world? I have looked in apples doc, but cannot find an answer. 

Edit: Assume I am using the new io6 feature of hosting the content through apple.

Answer: 
Yes, as a matter of fact, provided that you do a few steps, you can keep track and systematically, efficiently keep track of what is downloaded.

> 1.Yes it's possible. Provided you keep a track of who has bought what pack (ie. keep a bool value as an NSUserDefault), then they will still have access to it (even if you add more stuff/levels to it).
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> 2.It depends what you mean by notified; they will know if they read the update comments when they install the update. Also you could just choose to alert them when the load the app after the update - your call.
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> 3.If you're submitting the code Apple will review it. Just think of it like any other update to an app. 

This is taken directly from here: [Update in-app purchase content for iOS app?](https://stackoverflow.com/questions/7780133/update-in-app-purchase-content-for-ios-app)

After you have updated your content for the app store, you can allow your users to **Restore Purchases** and obtain the updated content!

Overall, have a mechanism to keep track of the version of the in-App purchases' version and then update when needed!

There is always, apple's own documentation: 
[Here you go! :)](http://developer.apple.com/library/ios/#documentation/StoreKit/Reference/SKDownload_Ref/Introduction/Introduction.html#//apple_ref/doc/uid/TP40011851) 

I hope this is clear and helpful!

EDIT:
After checking the user's content version number and finding that it's outdated, you would call the method (by the way, you would probably implement this checking mechanism in your app delegate.

```
[[SKPaymentQueue defaultQueue] restoreCompletedTransactions];

```

This would restore the transactions, but make sure you also need to include the rest of the implementation code!

I assume you know the code to restore in app purchases, but if not, here are a couple good links!

[Restore already bought in-app-purchases on iPhone?](https://stackoverflow.com/questions/7761556/restore-already-bought-in-app-purchases-on-iphone)

<http://www.iosdeveloperguide.com/in-app-purchase-heads-up-to-avoid-app-rejection/>

<http://appotography.com/2011/07/06/restoring-purchases-on-iphone-and-ipad/>
**About AppStore Hosted Content**

I have not tried, but browsing inside Apple doc, I've found [this](https://developer.apple.com/library/ios/#documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/13_ManagingIn-AppPurchases/ManagingIn-AppPurchases.html#//apple_ref/doc/uid/TP40011225-CH4-SW37) which confirms that you can upload multiple versions of a digital content hosted by Apple.

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> "You can have multiple versions of hosted content, but each one needs to be approved by Apple before it can be purchased by users."
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Also, you can check [this](http://www.absoluteripple.com/1/post/2013/01/apple-in-app-purchase-creating-app-store-hosted-content.html) and [this](http://www.techotopia.com/index.php/Configuring_and_Creating_App_Store_Hosted_Content_for_iOS_6_In-App_Purchases) tutorials, that shows that you have to specify the `Content Version` and `IAP ProductIdentifier` in the `ContentInfo.plist` when you create an App Store Hosted Content with Xcode.

![IAPHostedContentPlist](https://i.stack.imgur.com/nRSSM.png)

**How to notify the users that content has changed**

This depends of how you implement your purchase system, the content delivery, and how you keep track of the "state of your purchased products". Usually we keep track of the version of the purchased products, thats means, we save the product\_id with the content version when the purchased content is downloaded. We can save this data in files or inside a DB locally. Also, you don't have to worry about non downloaded (and non purchased) products, those do not need an update. When you update your in-app store with the last information of your available products (via update button, or app launch, or whatever you implemented) you should compare the last content versions with those you have downloaded, then you can notify the user that an update of his purchased product is available. Finally, you have to enable the download for that product.