Chapter 6 Task

mfromin · April 24th, 2011, 07:25 PM

When I complete the Core Data model at the end of Chapter 6 it compiles but if I try to run the app on the iPhone simulator I get an error and the app won't run.

Should the app be capable of running at that point?

The error I get is:

Code:

[Session started at 2011-04-24 17:15:56 -0600.]
2011-04-24 17:15:57.206 Tasks[822:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'executeFetchRequest:error: A fetch request must have an entity.'
*** Call stack at first throw:
(
	0   CoreFoundation                      0x00fa15a9 __exceptionPreprocess + 185
	1   libobjc.A.dylib                     0x010f5313 objc_exception_throw + 44
	2   CoreData                            0x00ccd05a -[NSManagedObjectContext executeFetchRequest:error:] + 3930
	3   CoreData                            0x00db08d0 -[NSFetchedResultsController performFetch:] + 1440
	4   Tasks                               0x0000336a -[RootViewController fetchedResultsController] + 739
	5   Tasks                               0x00002e01 -[RootViewController numberOfSectionsInTableView:] + 36
	6   UIKit                               0x004756ff -[UITableViewRowData(UITableViewRowDataPrivate) _updateNumSections] + 111
	7   UIKit                               0x004753b0 -[UITableViewRowData invalidateAllSections] + 66
	8   UIKit                               0x0032cd23 -[UITableView(_UITableViewPrivate) _updateRowData] + 113
	9   UIKit                               0x0032848f -[UITableView numberOfSections] + 39
	10  UIKit                               0x004c4165 -[UITableViewController viewWillAppear:] + 100
	11  Tasks                               0x00002b00 -[RootViewController viewWillAppear:] + 67
	12  UIKit                               0x003789be -[UINavigationController _startTransition:fromViewController:toViewController:] + 858
	13  UIKit                               0x0037332a -[UINavigationController _startDeferredTransitionIfNeeded] + 266
	14  UIKit                               0x0048e2e9 -[UILayoutContainerView layoutSubviews] + 226
	15  QuartzCore                          0x01f41a5a -[CALayer layoutSublayers] + 181
	16  QuartzCore                          0x01f43ddc CALayerLayoutIfNeeded + 220
	17  QuartzCore                          0x01ee90b4 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 310
	18  QuartzCore                          0x01eea294 _ZN2CA11Transaction6commitEv + 292
	19  UIKit                               0x002bc9c9 -[UIApplication _reportAppLaunchFinished] + 39
	20  UIKit                               0x002bce83 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 690
	21  UIKit                               0x002c7617 -[UIApplication handleEvent:withNewEvent:] + 1533
	22  UIKit                               0x002bfabf -[UIApplication sendEvent:] + 71
	23  UIKit                               0x002c4f2e _UIApplicationHandleEvent + 7576
	24  GraphicsServices                    0x018f9992 PurpleEventCallback + 1550
	25  CoreFoundation                      0x00f82944 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 52
	26  CoreFoundation                      0x00ee2cf7 __CFRunLoopDoSource1 + 215
	27  CoreFoundation                      0x00edff83 __CFRunLoopRun + 979
	28  CoreFoundation                      0x00edf840 CFRunLoopRunSpecific + 208
	29  CoreFoundation                      0x00edf761 CFRunLoopRunInMode + 97
	30  UIKit                               0x002bc7d2 -[UIApplication _run] + 623
	31  UIKit                               0x002c8c93 UIApplicationMain + 1160
	32  Tasks                               0x00002164 main + 102
	33  Tasks                               0x000020f5 start + 53
	34  ???                                 0x00000001 0x0 + 1
)
terminate called after throwing an instance of 'NSException'

mfromin · April 24th, 2011, 07:34 PM

I figured it out - seems that the code in the RootViewController is expecting the "default" entity and not the model we created in Chapter 6. There were several methods in the controller that called Entities or Attributes that did not exist because we had created the new model.

Would have been helpful for the book to tell us not to try to run the app at the end of Chapter 6.

--Michael