- (void)onPurchaseCompleted {
  GAITransaction *transaction =
  [GAITransaction transactionWithId:@"0_123456"            // (NSString) Transaction ID, should be unique.
                    withAffiliation:@"In-App Store";       // (NSString) Affiliation

transaction.taxMicros = (int64_t)(0.17 * 1000000);           // (int64_t) Total tax (in micros)
  transaction.shippingMicros = (int64_t)(0);                   // (int64_t) Total shipping (in micros)
  transaction.revenueMicros = (int64_t)(2.16 * 1000000);       // (int64_t) Total revenue (in micros)

[transaction addItemWithSKU:@"L_789"                         // (NSString) Product SKU
                     name:@"Level Pack: Space"             // (NSString) Product name
                 category:@"Game expansions"               // (NSString) Product category
              priceMicros:(int64_t)(1.99 * 1000000)        // (int64_t)  Product price (in micros)
                 quantity:1];                              // (NSInteger)  Product quantity

   [[GAI sharedInstance].defaultTracker sendTransaction:transaction]; // Send the transaction.
   }