Fix to ensure restoreTransactions completion callback is called robotmedia#150

Inside RMStore, when the paymentQueue:updatedTransactions is called after a restore, a pendingRestoredTransactions counter was incremented/decremented as transactions were processed. However, in our case updateTransactions callback was called twice, so 2x the amount of transactions were added to the pendingRestoredTransactions counter. The problem was the counter was incremented twice but only decremented once for each transaction. WHen the code reached notifyRestoreTransactionFinishedIfApplicableAfterTransaction, the counter was checked but was not equal to zero, so the callback wasn't called, even though all the transactions were processed.

The fix was to use a MutableSet to store transaction identifiers that were pending restore, which prevents duplicate transactions to be handled. The callback is now always called after transactions are restored.

Author: everappz

RMStore/RMStore.m

@@ -138,7 +138,7 @@ @implementation RMStore {
 
     NSMutableArray *_storedStorePayments;
 
-    NSInteger _pendingRestoredTransactionsCount;
+    NSMutableSet *_pendingRestoredTransactionIds;
     BOOL _restoredCompletedTransactionsFinished;
 
     SKReceiptRefreshRequest *_refreshReceiptRequest;
@@ -158,6 +158,7 @@ - (instancetype) init
         _productsRequestDelegates = [NSMutableSet set];
         _restoredTransactions = [NSMutableArray array];
         _storedStorePayments = [NSMutableArray array];
+        _pendingRestoredTransactionIds = [NSMutableSet set];
         [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
     }
     return self;
@@ -265,7 +266,7 @@ - (void)restoreTransactionsOnSuccess:(void (^)(NSArray *transactions))successBlo
                              failure:(void (^)(NSError *error))failureBlock
 {
     _restoredCompletedTransactionsFinished = NO;
-    _pendingRestoredTransactionsCount = 0;
+    [_pendingRestoredTransactionIds removeAllObjects];
     _restoredTransactions = [NSMutableArray array];
     _restoreTransactionsSuccessBlock = successBlock;
     _restoreTransactionsFailureBlock = failureBlock;
@@ -278,7 +279,7 @@ - (void)restoreTransactionsOfUser:(NSString*)userIdentifier
 {
     NSAssert([[SKPaymentQueue defaultQueue] respondsToSelector:@selector(restoreCompletedTransactionsWithApplicationUsername:)], @"restoreCompletedTransactionsWithApplicationUsername: not supported in this iOS version. Use restoreTransactionsOnSuccess:failure: instead.");
     _restoredCompletedTransactionsFinished = NO;
-    _pendingRestoredTransactionsCount = 0;
+    [_pendingRestoredTransactionIds removeAllObjects];
     _restoreTransactionsSuccessBlock = successBlock;
     _restoreTransactionsFailureBlock = failureBlock;
     [[SKPaymentQueue defaultQueue] restoreCompletedTransactionsWithApplicationUsername:userIdentifier];
@@ -593,9 +594,13 @@ - (void)didFailTransaction:(SKPaymentTransaction *)transaction queue:(SKPaymentQ
 
 - (void)didRestoreTransaction:(SKPaymentTransaction *)transaction queue:(SKPaymentQueue*)queue
 {
-    RMStoreLog(@"transaction restored with product %@", transaction.originalTransaction.payment.productIdentifier);
+    NSString *productIdentifier = transaction.originalTransaction.payment.productIdentifier;
+    RMStoreLog(@"transaction restored with product %@", productIdentifier);
 
-    _pendingRestoredTransactionsCount++;
+    if (productIdentifier)
+    {
+        [_pendingRestoredTransactionIds addObject:productIdentifier];
+    }
     if (self.receiptVerifier != nil)
     {
         [self.receiptVerifier verifyTransaction:transaction success:^{
@@ -695,9 +700,14 @@ - (void)notifyRestoreTransactionFinishedIfApplicableAfterTransaction:(SKPaymentT
     if (transaction != nil)
     {
         [_restoredTransactions addObject:transaction];
-        _pendingRestoredTransactionsCount--;
+        
+        NSString *productIdentifier = transaction.payment.productIdentifier;
+        if (productIdentifier)
+        {
+            [_pendingRestoredTransactionIds removeObject:productIdentifier];
+        }
     }
-    if (_restoredCompletedTransactionsFinished && _pendingRestoredTransactionsCount == 0)
+    if (_restoredCompletedTransactionsFinished && _pendingRestoredTransactionIds.count == 0)
     { // Wait until all restored transations have been verified
         NSArray *restoredTransactions = [_restoredTransactions copy];
         if (_restoreTransactionsSuccessBlock != nil)