Once the transaction has been done on your device, sometimes might so happen that your app gets deleted or removed then it needs to be re-installed on that device. In that case in order to show or highlight all the items that were already purchased , we are required to restore all the transactions. You can either add a button to restore all first or to restore all purchased on click any button going to purchase. It will restore all the ids of the purchased items.

// Method call to restore all the transactions that have been done.
 
 NSMutableArray*  _productIdsArray = [[NSMutableArrayalloc] init];
[[SKPaymentQueuedefaultQueue] restoreCompletedTransactions];

- (void) paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions

{

 for (SKPaymentTransaction *transaction in transactions)

    {

        switch (transaction.transactionState)

        {

            caseSKPaymentTransactionStatePurchased:

//NSLog(@"Purchase");

[selfcompletedPurchaseTransaction:transaction];

                break;

            caseSKPaymentTransactionStateFailed:

//NSLog(@"Failed");

[selfhandleFailedTransaction:transaction];

                break;

            caseSKPaymentTransactionStateRestored:

//NSLog(@"restoring");

[self restoreTransaction:transaction];

break;

caseSKPaymentTransactionStatePurchasing:

//NSLog(@"Puchasing");

break;

            default:

                break;

        }

    }

 

}

 - (void) restoreTransaction: (SKPaymentTransaction *)transaction

{

NSLog(@"Transaction info = %@",transaction.description);

 

[selfprovideContent: transaction.originalTransaction.payment.productIdentifier];

[[SKPaymentQueuedefaultQueue] finishTransaction: transaction];

}

 - (void) provideContent: (NSString*)productId
{

[_productIdsArray addObject:productId];

}

 
// _productIdsArray contains all the ids of the already purchased items.
 
// call back methods 
- (void) paymentQueueRestoreCompletedTransactionsFinished:(SKPaymentQueue *)queue

- (void) paymentQueue:(SKPaymentQueue *)queue restoreCompletedTransactionsFailedWithError:(NSError *)error