What does assertion failure mean in xcode?

What does assertion failure mean in xcode?

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outdated tutorial and hopefully use it as a learning experience.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.
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.
Code causing crash:
- (NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section
{
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView
dequeueReusableCellWithIdentifier:@"ChecklistItem"];
return cell;
}
Here is the stack trace:
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
Kind regards