title: libc abi.dylib: terminating with uncaught exception of type NSException CollectionView
body: <p>when i run my app, i received this error :<br></p>
  
  <p><pre>2014-08-11 10:52:10.546 ControlViewTest[918:60b] -[UIViewController collectionView:numberOfItemsInSection:]: unrecognized selector sent to instance 0x8c862f0
  2014-08-11 10:52:10.605 ControlViewTest[918:60b] <strong>* Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[UIViewController collectionView:numberOfItemsInSection:]: unrecognized selector sent to instance 0x8c862f0'
  *</strong> First throw call stack:
  (
      0   CoreFoundation                      0x017ec1e4 <strong>exceptionPreprocess + 180
      1   libobjc.A.dylib                     0x0156b8e5 objc_exception_throw + 44
      2   CoreFoundation                      0x01889243 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
      3   CoreFoundation                      0x017dc50b ___forwarding_</strong> + 1019
      4   CoreFoundation                      0x017dc0ee _CF_forwarding_prep_0 + 14
      5   UIKit                               0x008b0c34 -[UICollectionViewData _updateItemCounts] + 331
      6   UIKit                               0x008b0ce1 -[UICollectionViewData _validateItemCounts] + 45
      7   UIKit                               0x008b2c64 -[UICollectionViewData numberOfSections] + 35
      8   UIKit                               0x0087d6ed -[UICollectionView numberOfSections] + 62
      9   UIKit                               0x0089d614 -[UICollectionViewFlowLayout(Internal) _getSizingInfos] + 205
      10  UIKit                               0x0089e48f -[UICollectionViewFlowLayout(Internal) _fetchItemsInfo] + 521
      11  UIKit                               0x00899fe2 -[UICollectionViewFlowLayout prepareLayout] + 157
      12  UIKit                               0x008b0d9d -[UICollectionViewData _prepareToLoadData] + 76
      13  UIKit                               0x008b15c5 -[UICollectionViewData validateLayoutInRect:] + 56
      14  UIKit                               0x00877603 -[UICollectionView layoutSubviews] + 173
      15  UIKit                               0x0029a964 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
      16  libobjc.A.dylib                     0x0157d82b -[NSObject performSelector:withObject:] + 70
      17  QuartzCore                          0x03c5745a -[CALayer layoutSublayers] + 148
      18  QuartzCore                          0x03c4b244 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
      19  QuartzCore                          0x03c573a5 -[CALayer layoutIfNeeded] + 160
      20  UIKit                               0x0035cae3 -[UIViewController window:setupWithInterfaceOrientation:] + 304
      21  UIKit                               0x00272aa7 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 5212
      22  UIKit                               0x00271646 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:] + 82
      23  UIKit                               0x00271518 -[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 117
      24  UIKit                               0x002715a0 -[UIWindow _setRotatableViewOrientation:duration:force:] + 67
      25  UIKit                               0x0027063a <strong>57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 120
      26  UIKit                               0x0027059c -[UIWindow _updateToInterfaceOrientation:duration:force:] + 400
      27  UIKit                               0x002712f3 -[UIWindow setAutorotates:forceUpdateInterfaceOrientation:] + 870
      28  UIKit                               0x002748e6 -[UIWindow setDelegate:] + 449
      29  UIKit                               0x0034eb77 -[UIViewController _tryBecomeRootViewControllerInWindow:] + 180
      30  UIKit                               0x0026a474 -[UIWindow addRootViewControllerViewIfPossible] + 591
      31  UIKit                               0x0026a5ef -[UIWindow _setHidden:forced:] + 312
      32  UIKit                               0x0026a86b -[UIWindow _orderFrontWithoutMakingKey] + 49
      33  UIKit                               0x002753c8 -[UIWindow makeKeyAndVisible] + 65
      34  UIKit                               0x00225bc0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 2097
      35  UIKit                               0x0022a667 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
      36  UIKit                               0x0023ef92 -[UIApplication handleEvent:withNewEvent:] + 3517
      37  UIKit                               0x0023f555 -[UIApplication sendEvent:] + 85
      38  UIKit                               0x0022c250 _UIApplicationHandleEvent + 683
      39  GraphicsServices                    0x037e1f02 _PurpleEventCallback + 776
      40  GraphicsServices                    0x037e1a0d PurpleEventCallback + 46
      41  CoreFoundation                      0x01767ca5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION</strong> + 53
      42  CoreFoundation                      0x017679db __CFRunLoopDoSource1 + 523
      43  CoreFoundation                      0x0179268c __CFRunLoopRun + 2156
      44  CoreFoundation                      0x017919d3 CFRunLoopRunSpecific + 467
      45  CoreFoundation                      0x017917eb CFRunLoopRunInMode + 123
      46  UIKit                               0x00229d9c -[UIApplication _run] + 840
      47  UIKit                               0x0022bf9b UIApplicationMain + 1225
      48  ControlViewTest                     0x0000264d main + 141
      49  libdyld.dylib                       0x01e33701 start + 1
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  (lldb)</pre><br>
  somebody can help me pls</p>