title: productsRequest response method is not calling
body: <p>I am implementing an in app purchase and I am sending the request to apple store through</p>
  
  <pre><code>- (void) requestProductData
  {
   SKProductsRequest *request= [[SKProductsRequest alloc] initWithProductIdentifiers:
           [NSSet setWithObjects: featureAId,featureBId,nil]]; // add any other product here
   request.delegate = self;
   [request start];
  }
  </code></pre>
  
  <p>the response method </p>
  
  <pre><code>- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
  {
   [purchasableObjects addObjectsFromArray:response.products];
  }
  </code></pre>
  
  <p>is not getting called at all. Only once did it call out of ten attempts I tried.</p>