Monetizing via the Apple App Store - Beginning iOS6 Games Development - page 244

Listing 10-2. ExtrasController.m (viewDidLoad)
#define PURCHASE_INGAME_SAUCERS @"com.beltcommander.ingame.saucers"
#define PURCHASE_INGAME_POWERUPS @"com.beltcommander.ingame.powerups"
//....
- (void)viewDidLoad
{
[super viewDidLoad];
idsToProducts = [NSMutableDictionary new];
[[SKPaymentQueue defaultQueue] addTransactionObserver:self];
//Get set of product ids
NSSet* potentialProducts = [NSSet setWithObjects:PURCHASE_INGAME_POWERUPS,
SKProductsRequest* request = [[SKProductsRequest alloc] initWithProductIdentifiers:potentialProducts];
[request setDelegate:self];
[request start];
[self setGameParams: [GameParameters readFromDefaults]];
viewDidLoad for the class ExtrasController . In this task, we start by
idsToProducts map and by getting the default SKPaymentQueue by calling defaultQueue ,
self as an observer. Because self conforms to the protocol SKPaymentTransactionObserver ,
ExtrasController will be informed of all changes in state for a purchase. Once we
have a registered observer, we create a set of known product IDs. In this case, the NSSet
potentialProducts is created from two constants: PURCHASE_INGAME_POWERUPS and PURCHASE_
INGAME_SAUCERS . As we can see, these constants are the same strings as we specified when we
created the products in iTunes Connect.
Once we have specified our set of potential products, we create an SKProductsRequest , set self as
the delegate, and call start on it. While StoreKit is working out which product IDs are valid, we call
setGameParams and specify that we should use the GameParameters object we have stored the default
NSUsersDefaults . When StoreKit has its results, the tasks productsRequest:didReceiveResponse: ,
as shown in Listing 10-3.
Listing 10-3. ExtrasController.m (productsRequest:didReceiveResponse:)
- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response {
for (SKProduct* aProduct in response.products){
if ([aProduct.productIdentifier isEqualToString:PURCHASE_INGAME_SAUCERS]){
[saucerButton setEnabled:YES];
[saucerButton setHidden:NO];
[idsToProducts setObject:aProduct forKey:PURCHASE_INGAME_SAUCERS];
} else if ([aProduct.productIdentifier isEqualToString:PURCHASE_INGAME_POWERUPS]){
[powerupButton setEnabled:YES];
[powerupButton setHidden:NO];
[idsToProducts setObject:aProduct forKey:PURCHASE_INGAME_POWERUPS];
}
}
}