title: Apple Mach-O Linker Error (IAP)
body: <p>I'm struggling with in-app purchases. Whenever I import StoreKit, I receive this error.<br>
  I've been at this for days with no luck.. Someone help?</p>
  
  <p>Header File:    </p>
  
  <pre><code>#import &lt;StoreKit/StoreKit.h&gt;    
  
  #define kInAppPurchaseManagerProductsFetchedNotification          @"kInAppPurchaseManagerProductsFetchedNotification"
  
  @interface InAppPurchaseManager : NSObject &lt;SKProductsRequestDelegate&gt;
  {
      SKProduct *proUpgradeProduct;
      SKProductsRequest *productsRequest;
  }
  @end
  </code></pre>
  
  <p>Implementation File:    </p>
  
  <pre><code>#import "IAPManager.h"
  
  @implementation InAppPurchaseManager 
  
  - (void)requestProUpgradeProductData
  {
      NSSet *productIdentifiers = [NSSet 
         setWithObject:@"com.runmonster.runmonsterfree.upgradetopro" ];
      productsRequest = [[SKProductsRequest alloc] initWithProductIdentifiers:productIdentifiers];
      productsRequest.delegate = self;
      [productsRequest start];
  }
  
  #pragma mark -
  #pragma mark SKProductsRequestDelegate methods
  
  - (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
  {
      NSArray *products = response.products;
      proUpgradeProduct = [products count] == 1 ? [[products firstObject] retain] : nil;
      if (proUpgradeProduct)
      {
          NSLog(@"Product title: %@" , proUpgradeProduct.localizedTitle);
          NSLog(@"Product description: %@" , proUpgradeProduct.localizedDescription);
          NSLog(@"Product price: %@" , proUpgradeProduct.price);
          NSLog(@"Product id: %@" , proUpgradeProduct.productIdentifier);
      }
  
      for (NSString *invalidProductId in response.invalidProductIdentifiers)
      {
          NSLog(@"Invalid product id: %@" , invalidProductId);
      }
  
  
      [productsRequest release];
  
      [[NSNotificationCenter defaultCenter] postNotificationName:kInAppPurchaseManagerProductsFetchedNotification object:self userInfo:nil];
  }
  @end
  </code></pre>
  
  <p>The error thats killing me:    </p>
  
  <pre><code>    Undefined symbols for architecture armv7:
        "_OBJC_CLASS_$_SKProductsRequest", referenced from:
            objc-class-ref in IAPManager.o
      ld: symbol(s) not found for architecture armv7
      collect2: ld returned 1 exit status
  
  "_OBJC_CLASS_$_SKProductsRequest", referenced from:    
  Objc-class-ref in IAPManager.o    
  Symbol(s) not found for architecture armv7    
  Collect2: Id returned 1 exit status
  </code></pre>