title: What does this assertion failure mean in a UITableViewDataSource?
body: <p>Currently following a checklists tutorial built with io6 in mind. I'm using xcode 5, ios7 sdk. The tutorial hasn't been updated for IOS7 but I didn't want to stop my learning so decided to go ahead and work with the outdated tutorial and hopefully use it as a learning experience. Using reading of official Apple docs and extensive googling as my guide along the way.</p>
  
  <p>Very early I've run into an issue already and not sure what is wrong. I noticed that the autocomplete had part of the methods below crossed out (a deprecation maybe?). The issue is definitely coming from the code below because once I remove it the simulator loads the app fine.</p>
  
  <p><strong>Code causing crash:</strong></p>
  
  <pre><code>- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
  {
      return 1;
  }
  - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
  {
      UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"ChecklistItem"];
      return cell;
  }
  </code></pre>
  
  <p><strong>Here is the stack trace:</strong></p>
  
  <pre><code>2013-09-28 20:51:26.208 Checklists[47289:a0b] *** Assertion failure in -[UITableView _configureCellForDisplay:forIndexPath:], /SourceCache/UIKit_Sim/UIKit-2903.2/UITableView.m:6235
  2013-09-28 20:51:26.218 Checklists[47289:a0b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x017335e4 __exceptionPreprocess + 180
      1   libobjc.A.dylib                     0x014b68b6 objc_exception_throw + 44
      2   CoreFoundation                      0x01733448 +[NSException raise:format:arguments:] + 136
      3   Foundation                          0x0109723e -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 116
      4   UIKit                               0x00311ae5 __53-[UITableView _configureCellForDisplay:forIndexPath:]_block_invoke + 426
      5   UIKit                               0x0028af5f +[UIView(Animation) performWithoutAnimation:] + 82
      6   UIKit                               0x0028afa8 +[UIView(Animation) _performWithoutAnimation:] + 40
      7   UIKit                               0x00311936 -[UITableView _configureCellForDisplay:forIndexPath:] + 108
      8   UIKit                               0x00317d4d -[UITableView _createPreparedCellForGlobalRow:withIndexPath:] + 442
      9   UIKit                               0x00317e03 -[UITableView _createPreparedCellForGlobalRow:] + 69
      10  UIKit                               0x002fc124 -[UITableView _updateVisibleCellsNow:] + 2378
      11  UIKit                               0x0030f5a5 -[UITableView layoutSubviews] + 213
      12  UIKit                               0x00293dd7 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
      13  libobjc.A.dylib                     0x014c881f -[NSObject performSelector:withObject:] + 70
      14  QuartzCore                          0x03aed72a -[CALayer layoutSublayers] + 148
      15  QuartzCore                          0x03ae1514 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
      16  QuartzCore                          0x03aed675 -[CALayer layoutIfNeeded] + 160
      17  UIKit                               0x0034eca3 -[UIViewController window:setupWithInterfaceOrientation:] + 304
      18  UIKit                               0x0026dd27 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 5212
      19  UIKit                               0x0026c8c6 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:] + 82
      20  UIKit                               0x0026c798 -[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 117
      21  UIKit                               0x0026c820 -[UIWindow _setRotatableViewOrientation:duration:force:] + 67
      22  UIKit                               0x0026b8ba __57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 120
      23  UIKit                               0x0026b81c -[UIWindow _updateToInterfaceOrientation:duration:force:] + 400
      24  UIKit                               0x0026c573 -[UIWindow setAutorotates:forceUpdateInterfaceOrientation:] + 870
      25  UIKit                               0x0026fb66 -[UIWindow setDelegate:] + 449
      26  UIKit                               0x00340dc7 -[UIViewController _tryBecomeRootViewControllerInWindow:] + 180
      27  UIKit                               0x002657cc -[UIWindow addRootViewControllerViewIfPossible] + 609
      28  UIKit                               0x00265947 -[UIWindow _setHidden:forced:] + 312
      29  UIKit                               0x00265bdd -[UIWindow _orderFrontWithoutMakingKey] + 49
      30  UIKit                               0x0027044a -[UIWindow makeKeyAndVisible] + 65
      31  UIKit                               0x002238e0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1851
      32  UIKit                               0x00227fb8 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
      33  UIKit                               0x0023c42c -[UIApplication handleEvent:withNewEvent:] + 3447
      34  UIKit                               0x0023c999 -[UIApplication sendEvent:] + 85
      35  UIKit                               0x00229c35 _UIApplicationHandleEvent + 736
      36  GraphicsServices                    0x036862eb _PurpleEventCallback + 776
      37  GraphicsServices                    0x03685df6 PurpleEventCallback + 46
      38  CoreFoundation                      0x016aedd5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
      39  CoreFoundation                      0x016aeb0b __CFRunLoopDoSource1 + 523
      40  CoreFoundation                      0x016d97ec __CFRunLoopRun + 2156
      41  CoreFoundation                      0x016d8b33 CFRunLoopRunSpecific + 467
      42  CoreFoundation                      0x016d894b CFRunLoopRunInMode + 123
      43  UIKit                               0x002276ed -[UIApplication _run] + 840
      44  UIKit                               0x0022994b UIApplicationMain + 1225
      45  Checklists                          0x00001b7d main + 141
      46  libdyld.dylib                       0x01d6f725 start + 0
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  </code></pre>