CODEWITHSUNDEEP
iosnsuserdefaultsicloud
dragos
dragos

Reputation: 300

Saving information about previous purchased items in iOS

I am working on an app that has a number of in app store purchase items that will enable certain functionality.

After each item is purchased, I would need to remember it (of course). I would also like to persist this information in iCloud in case the app is deleted or is installed on another device.

What is the best data structure to be used?

Can user defaults database be used for this?

What is important is that the user will not have access to change those values and enable by themselves the paid functionality.

Upvotes: 1

Views: 137

Answers (2)

rmaddy
rmaddy

Reputation: 318904

I use the KeychainItemWrapper class to store a flag in the keychain. The nice thing is, so far, is that the keychain survives an app deletion. IF the user then reinstalls the same app on the same device, the keychain data is still there.

There is no need to use iCloud. If the user installs your app on another device, you just need to provide a "Restore Purchases" button in your app. Then you call the Store Kit APIs to restore existing purchases. The "In-App Purchasing Programming Guide" covers how to do this.

This same functionality will allow a user to restore their purchases even if the flags in the keychain are lost.

Upvotes: 0

user529758
user529758

Reputation:

Can user defaults database be used for this?

It can, but it's not the best idea to do so, since

What is important is that the user will not have access to change those values and enable by themselves the paid functionality.

and NSUserDefaults stores its contents as binary or plaintext property lists. Easily changeable on a jailbroken device. (Also changeable on a non-jailbroken one by modifying the iTunes backup files).

What you could do is either store them in the keychain, although the keychain is not really designed for this (and it can also be dumped on a jailbroken device using Ptoomey3's awesome Kaychain-Dumper tool), or better store it remotely on your server and let your server check what the user has purchased.

Of course, if it's not only the server that does the check, so for example you don't only send or don't send content based on purchases, but you also use this check for performing actions within your app, then it also can be hacked (google "MobileSubstrate cheat DoodleJump" for a nice example).

All in all: there's no perfectly secure system.

Upvotes: 0

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