Question

How it works – The app is a subscription to a service that works cross platform. On the iphone the initial purchase will get you 30 days of full functionality then after 30 days you can’t do ceirtain things until you buy a subscription with an in app purchase.

What I need – I need to know if it was the first run so that I can add the users info to the database. Or because it is cross platform they may have already paid for a subscription so I need to add 30 days to the user’s already existing subscription.

What I am doing now – Currently I am storing the identifierForVendor in the remote database and in NSUserDefaults there is a bool checked to see 1. if it is the first run and 2. if it is the first run to allow the user to add themselves to the database for a 30 day full use, or to add 30 days to their existing subscription.

The Problem – The problem is that if the user deletes the app then reinstalls it the NSUserDefaults will be deleted too, and the identifierForVendor will change and that will allow the user to add another 30 days to their subscription for free just by deleting and reinstalling the app.

Ideal Solution I originally wanted to do a subscription for the app, but I didn’t know how to check the receipt when the app is originally purchased and insert the user into the remote database. Also I don’t really know how to setup a subscription that isn’t an In App Purchase. I also thought about making the app free and then they can use the In App Purchase to buy the service but the app is useless without being able to connect to the remote server to build up data in the first place.

Bottom Line I would like to do one of the following

1. Make the subscription on the first purchase (I need to be able to detect if the purchase is valid so I can enter the user info into the remote database)
2. Make the app free then use In App Purchase to add subscription (Is it acceptable to have a free app that won’t do anything until you subscribe?)
3. Leave it the way it is now (but find a more permanent solution to the identifierForVendor, and the identifierForAdvertising won’t work either because it can be turned off)

Answer 1

This will help you so much. Basically it’s a wrapper for Keychain that is patterned after NSUserDefaults. It heled me a lot. Storing things in the Keychain makes them stay past app reinstalls.

https://github.com/carlbrown/PDKeychainBindingsController

This project is intended to make using the Mac OSX and iOS Keychains
as easy as NSUserDefaults.

It is a KVO-compliant Cocoa wrapper around the Mac OSX and iOS
Keychains, and the model for this wrapper is NSUserDefaults, so the
intent is that for the common cases you would normally want to call:

[NSUserDefaultsController sharedUserDefaultsController] You should be
able to call

[PDKeychainBindingsController sharedKeychainBindingsController] And
for the common cases you normally would have called:

[NSUserDefaults standardUserDefaults] You should be able to call

[PDKeychainBindings sharedKeychainBindings]