Copying data from a free iOS version to a full version of my app?

Question

How could a full version of my iOS app access / copy the database / settings from the free version ?

I'm thinking of providing a free version of my app and I can't see how people then buying the full version could get access to the data from my free version ?

Answer 1

All apps are isolated on iOS. They are installed as different iOS system users. One user do not have permission to access another user's files. In the old times, one common approach to address this problem is to enable iTunes file sharing. And tell users to manually copy the files.

Your better bet is to use the freemium model to sell your app. Make the app free, and unlock extra features via in-app-purchase. This way, your files, documents, settings won't need transferring to the pro version. The app itself becomes pro after unlocking.

Here is the guide from Apple: https://developer.apple.com/library/ios/#documentation/NetworkingInternet/Conceptual/StoreKitGuide/Introduction/Introduction.html (though not very intuitive).

The walkthrough here: http://troybrant.net/blog/2010/01/in-app-purchases-a-full-walkthrough/ is very helpful.

Last but not least, be aware that in-app-purchase is crackable. So please read: How to detect "IAP crackers"? , Verifying In App Purchase Receipt from Client , and https://stackoverflow.com/questions/4715414/apple-in-app-purchase-verify-receipt , verify in app purchase , In App Purchase Receipt verification within app .

Note that you are supposed to setup a server to validate iap receipts. Though it's doable from within the app, it's not safe. As far as I can remember, you can test in-app-purchase through StoreKit in iOS simulator v5.0, that should be Xcode 4.2. Before that, it can only be tested on a device.

@Dominik Hadl mentioned you can use a server to sync the file. The operation is usually complicated. If you prefer this idea, you can choose to use custom url scheme to launch one app from another to ease the operation. See steps below:

1. User press "Begin sync" in the free app to upload the file to your server
2. Server return the ID of the file to the free app
3. User press "Launch Pro App and Download my file", which leads to a custom url scheme to launch your Pro version (must be installed first), with the file ID
4. Pro version use the file ID to download that file directly