Recovering app-in purchases in iOS app

In our iOS app, we have a system of in-app purchases which arenon-consumable. All in-app purchases is working already. We would lke to allow a user to recover app-in purchases if he has unistall and reinstall the app or he is in a new phone. We would like to put this choice in the Settings button ("Recover") and launch the process. To clarify the process is the following: 1) The user buys something in the app 2) In the app, after validation of buying coming by Apple, we put a variable to true to unblock the corresponding purchase. 3) If he unistall the app we miss the information of this variable to "true" When reinstalling the app 1) Open the app 2) Go to settings and click to a button "Recover purchases" 3) When clicking, it calls the service of Apple and with the user id he get all already bought in our app. 4) The variable that controls the purchase is set to "true" as the first time he bought.