title: Unwind segue issue when navigating back to parent scene
body: <p>I'm trying to unwind segue form a scene. It works fine but I need to get a value to the parent screen. (I use the push segue to navigate from parent to child scene)</p>
  
  <p>I'm calling the unwind segue like this</p>
  
  <pre><code>- (IBAction)done:(UIStoryboardSegue *)segue {
      NSLog(@"gonna navigate");
      RESTToppingTableViewController *vc = [segue destinationViewController];
      [self setSelectedToppings:[vc toppingList]];
      NSLog(@"%@", [vc toppingList]);
  }
  </code></pre>
  
  <p>But the issue is, it seems the <code>toppingList</code> array is removed from memory even before the parent view is called.</p>
  
  <p>Below is the error I got.</p>
  
  <pre><code>2013-12-06 13:26:42.192 Pizza to Go[2319:a0b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[RESTAddToCartViewController toppingList]: unrecognized selector sent to instance 0x9b681a0'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x01f405e4 __exceptionPreprocess + 180
      1   libobjc.A.dylib                     0x01cc38b6 objc_exception_throw + 44
      2   CoreFoundation                      0x01fdd903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
      3   CoreFoundation                      0x01f3090b ___forwarding___ + 1019
      4   CoreFoundation                      0x01f304ee _CF_forwarding_prep_0 + 14
      5   Pizza to Go                         0x0004a3a2 -[RESTAddToCartViewController done:] + 130
      6   libobjc.A.dylib                     0x01cd581f -[NSObject performSelector:withObject:] + 70
      7   UIKit                               0x010d01f1 -[UIStoryboardUnwindSegueTemplate _perform:] + 536
      8   UIKit                               0x00f660f9 -[UIStoryboardSegueTemplate perform:] + 115
      9   libobjc.A.dylib                     0x01cd5874 -[NSObject performSelector:withObject:withObject:] + 77
      10  UIKit                               0x00a330c2 -[UIApplication sendAction:to:from:forEvent:] + 108
      11  UIKit                               0x00d07c9b -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 139
      12  libobjc.A.dylib                     0x01cd5874 -[NSObject performSelector:withObject:withObject:] + 77
      13  UIKit                               0x00a330c2 -[UIApplication sendAction:to:from:forEvent:] + 108
      14  UIKit                               0x00a3304e -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 61
      15  UIKit                               0x00b2b0c1 -[UIControl sendAction:to:forEvent:] + 66
      16  UIKit                               0x00b2b484 -[UIControl _sendActionsForEvents:withEvent:] + 577
      17  UIKit                               0x00b2a733 -[UIControl touchesEnded:withEvent:] + 641
      18  UIKit                               0x00a7051d -[UIWindow _sendTouchesForEvent:] + 852
      19  UIKit                               0x00a71184 -[UIWindow sendEvent:] + 1232
      20  UIKit                               0x00a44e86 -[UIApplication sendEvent:] + 242
      21  UIKit                               0x00a2f18f _UIApplicationHandleEventQueue + 11421
      22  CoreFoundation                      0x01ec983f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
      23  CoreFoundation                      0x01ec91cb __CFRunLoopDoSources0 + 235
      24  CoreFoundation                      0x01ee629e __CFRunLoopRun + 910
      25  CoreFoundation                      0x01ee5ac3 CFRunLoopRunSpecific + 467
      26  CoreFoundation                      0x01ee58db CFRunLoopRunInMode + 123
      27  GraphicsServices                    0x03e159e2 GSEventRunModal + 192
      28  GraphicsServices                    0x03e15809 GSEventRun + 104
      29  UIKit                               0x00a31d3b UIApplicationMain + 1225
      30  Pizza to Go                         0x000574ad main + 141
      31  libdyld.dylib                       0x0285e725 start + 0
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  </code></pre>
  
  <p>What could be the possible fix? thanks for your time in advance.</p>