What does this Objective-C dictionary code do?

Question

.h

@property (nonatomic, strong) NSMutableDictionary * products;  //not synthesized in .m

.m

- (void)productsRequest:(SKProduct         


        

Answer 1

It's not IAPProduct *product= NSMutableDictionary[NSArray.productIdentifier];

The type of skProduct is SKProduct, not NSArray. The fast enumeration for (SKProduct * skProduct in skProducts) loops through all elements in skProducts as SKProduct.

It's (to some extent) like using a loop with a counter doing:

//for (SKProduct * skProduct in skProducts)
for (int i=0; i<skProducts.count; i++)
{
    SKProduct *skProduct = skProduct[i];
    IAPProduct * product = _products[skProduct.productIdentifier];
    product.skProduct = skProduct;
    product.availableForPurchase = YES;
}

Answer 2

You are having trouble understanding this line:

IAPProduct * product = _products[skProduct.productIdentifier];

Lets break it down:

NSString *key = skProduct.productIdentifier;
IAPProduct * product = _products[key];

The 2nd line is modern syntax for:

IAProduct * product = [_products objectForKey:key];

This is the normal way to lookup a value in a dictionary for a given key.