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POMy iPhone core data app runs perfectly the first time but crashes when run after that
 

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  1. POMy iPhone core data app runs perfectly the first time but crashes when run after that
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    <p>my app is based around two classes: <code>Jam</code> and <code>JamItem</code>, each with a TableViewController to display / add items.<br/><br/></p> <p>The model contains two entities for the two classes, and there is an optional one-to-one relationship between them. <code>JamItem</code> has a name field and a price field. <code>Jam</code> has a quantity field. There are corresponding <code>NSManagedObject</code> classes for the two entities.<br/><br/></p> <p>Both lists are based on table list view controllers and were modelled on the Recipes example on the Apple site. The <code>JamListTableViewController</code> displays all <code>JamItem</code> instances that have been added to the list. When I click add, a new instance of <code>JamItemListTableViewController</code> is created and pushed onto the nav stack. This lists <code>JamItem</code> instances that have been created. When a <code>JamItem</code> is selected, the <code>- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath</code> method creates an instance of <code>JamItem</code> and passes it back via a delegate to <code>JamListTableViewController</code>. This then creates a new instance of <code>Jam</code> and adds the <code>JamItem</code> to it and then saves.<br/><br/></p> <p><strong>I can run the app perfectly when it is fresh on the simulator and run the first time with a clean database!</strong><br><br></p> <p>The <code>JamItemListTableViewController</code> always works and I can happily add and remove 'jam items' from the list. However, if I stop the app and re-run, then try to add a new <code>JamItem</code> to the jam list (<code>JamListTableViewController</code>), it crashes when <code>JamListTableViewController</code> calls the <code>[jam.managedObjectContext save:&amp;error]</code> and I get the error below, which I think is where it is trying to sort by name.<br><br></p> <p>The <code>NSFetchedResultsController</code> in <code>JamItemListTableViewController</code> is configured to order by name. The <code>NSFetchedResultsController</code> in <code>JamItemListTableViewController</code> is ordered by <code>JamItem.name</code><br/><br/></p> <p>I hope this makes sense as I have been pulling my hair out for weeks now trying to find the solution. I think I might have (or have not) released an object, which is causing the <code>JamItem</code> list to flag that it has been updated and start trying to re-sort its list.<br/><br/></p> <p>This is the dump of the error:<br/><br/></p> <pre><code>2010-09-29 07:20:00.443 Jams[12451:207] Serious application error. Exception was caught during Core Data change processing. This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification. [&lt;UINavigationItem 0x5b4dc30&gt; valueForUndefinedKey:]: this class is not key value coding-compliant for the key name. with userInfo { NSTargetObjectUserInfoKey = "&lt;UINavigationItem: 0x5b4dc30&gt;"; NSUnknownUserInfoKey = name; } 2010-09-29 07:20:00.446 Jams[12451:207] *** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[&lt;UINavigationItem 0x5b4dc30&gt; valueForUndefinedKey:]: this class is not key value coding-compliant for the key name.' *** Call stack at first throw: ( 0 CoreFoundation 0x02577919 __exceptionPreprocess + 185 1 libobjc.A.dylib 0x026c55de objc_exception_throw + 47 2 CoreFoundation 0x02577851 -[NSException raise] + 17 3 Foundation 0x000d96b1 -[NSObject(NSKeyValueCoding) valueForUndefinedKey:] + 279 4 Foundation 0x00040868 _NSGetUsingKeyValueGetter + 147 5 Foundation 0x0003fd2e -[NSObject(NSKeyValueCoding) valueForKey:] + 278 6 Foundation 0x00043535 -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 381 7 Foundation 0x000f7c4f -[NSSortDescriptor compareObject:toObject:] + 128 8 CoreData 0x0237cb5e +[NSFetchedResultsController(PrivateMethods) _insertIndexForObject:inArray:lowIdx:highIdx:sortDescriptors:] + 286 9 CoreData 0x0237d1b2 -[NSFetchedResultsController(PrivateMethods) _postprocessInsertedObjects:] + 402 10 CoreData 0x023831bc -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 1804 11 Foundation 0x00035c1d _nsnote_callback + 145 12 CoreFoundation 0x0254fcf9 __CFXNotificationPost_old + 745 13 CoreFoundation 0x024cf11a _CFXNotificationPostNotification + 186 14 Foundation 0x0002b7c2 -[NSNotificationCenter postNotificationName:object:userInfo:] + 134 15 CoreData 0x022bf519 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 89 16 CoreData 0x0232eb33 -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 259 17 CoreData 0x022a1f78 -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 1352 18 CoreData 0x022dba15 -[NSManagedObjectContext save:] + 149 19 JamsApp 0x000064b3 -[JamsListTableViewController insertJamItem:] + 168 20 JamsApp 0x00006405 -[JamsListTableViewController selectedJamItem:] + 43 21 JamsApp 0x00003f41 -[JamItemListTableViewController tableView:didSelectRowAtIndexPath:] + 143 22 UIKit 0x0033d718 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1140 23 UIKit 0x00333ffe -[UITableView _userSelectRowAtIndexPath:] + 219 24 Foundation 0x0004acea __NSFireDelayedPerform + 441 25 CoreFoundation 0x02558d43 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19 26 CoreFoundation 0x0255a384 __CFRunLoopDoTimer + 1364 27 CoreFoundation 0x024b6d09 __CFRunLoopRun + 1817 28 CoreFoundation 0x024b6280 CFRunLoopRunSpecific + 208 29 CoreFoundation 0x024b61a1 CFRunLoopRunInMode + 97 30 GraphicsServices 0x02ddc2c8 GSEventRunModal + 217 31 GraphicsServices 0x02ddc38d GSEventRun + 115 32 UIKit 0x002d9b58 UIApplicationMain + 1160 33 JamsApp 0x00001c0c main + 102 34 JamsApp 0x00001b9d start + 53 ) terminate called after throwing an instance of 'NSException' </code></pre>
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