问productsRequest响应方法未调用

EN

- (void) requestProductData
{
 SKProductsRequest *request= [[SKProductsRequest alloc] initWithProductIdentifiers:
         [NSSet setWithObjects: featureAId,featureBId,nil]]; // add any other product here
 request.delegate = self;
 [request start];
}

- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
{
 [purchasableObjects addObjectsFromArray:response.products];
}