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POCore Data: EXC_BAD_ACCESS accessing relationship
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  1. POCore Data: EXC_BAD_ACCESS accessing relationship
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    copied!<p>I have a crash in a simple Core Data project.</p> <p>I created a new, empty iPhone project with Core Data. Two entities are added to the data model with a to-one, inverse relationship between them. Both have auto-generated NSManagedObject subclasses. The entity Name and Class are set on both.</p> <pre><code>DBMove attribute: moveValue:Integer16 relationship: newPosition -&gt; DBPosition (inverse: move) DBPosition attribute: positionValue:Integer16 relationship: move -&gt; DBMove (inverse: newPosition) </code></pre> <p>There is a custom view controller that creates a DBMove and DBPosition. It then sets the inverse relationship between them and saves it. The managed object context is retrieved from the app delegate; I think this is safe because [NSThread isMultiThreaded] returns false.</p> <pre><code>- (void)newEntries { AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext *context = appDelegate.managedObjectContext; DBPosition *newPos = [NSEntityDescription insertNewObjectForEntityForName:@"DBPosition" inManagedObjectContext:context]; newPos.positionValue = [NSNumber numberWithInt:5]; DBMove *newMove = [NSEntityDescription insertNewObjectForEntityForName:@"DBMove" inManagedObjectContext:context]; newMove.moveValue = [NSNumber numberWithInt:2]; newPos.move = newMove; NSError *error; if (![context save:&amp;error]) { NSLog(@"Save error: %@", [error localizedDescription]); } } </code></pre> <p>The view controller then fetches all the DBMoves. Their Integer16 attributes output as expected. <strong>[Edit]</strong> Accessing the relationship causes EXC_BAD_ACCESS in main::@autoreleasepool to occur sometime after looping through <strong>all</strong> the fetch results. Before the crash, all entries of DBMove and DBPosition in the database from previous program runs all print correctly, followed by NSLogs from my ViewController init; the crash appears delayed. It occurs about every 4 out of 5 program runs. <strong>[End Edit]</strong></p> <pre><code>- (void)printMoves { AppDelegate *appDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate]; NSManagedObjectContext *context = appDelegate.managedObjectContext; NSError *error; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"DBMove" inManagedObjectContext:context]; [fetchRequest setEntity:entity]; NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&amp;error]; for (DBMove *move in fetchedObjects) { DBPosition *newPos = move.newPosition; // &lt;--- all's well without this reference! NSLog(@"Move : %d", [move.moveValue intValue]); NSLog(@"Position : %d", [newPos.positionValue intValue]); } } </code></pre> <p>NSZombieEnabled=YES causes the program to run without fail and print the expected values. My context appears to be the same throughout the whole execution.</p> <p>Here is the stack trace:</p> <pre><code>#0 0x018300b2 in objc_msgSend () #1 0x00256ffc in -[_CDSnapshot dealloc] () #2 0x0025573d in -[_CDSnapshot release] () #3 0x00260384 in -[NSManagedObject(_NSInternalMethods) _clearRawPropertiesWithHint:] () #4 0x0026018b in -[NSFaultHandler turnObject:intoFaultWithContext:] () #5 0x002607ba in -[NSManagedObject dealloc] () #6 0x00257b88 in -[_PFManagedObjectReferenceQueue _processReferenceQueue:] () #7 0x00232fe1 in _performRunLoopAction () #8 0x01a654ce in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ () #9 0x01a6541f in __CFRunLoopDoObservers () #10 0x01a43344 in __CFRunLoopRun () #11 0x01a42ac3 in CFRunLoopRunSpecific () #12 0x01a428db in CFRunLoopRunInMode () #13 0x038fe9e2 in GSEventRunModal () #14 0x038fe809 in GSEventRun () #15 0x0058ed3b in UIApplicationMain () #16 0x0000396d in main at /Users/brian/devel/test2-CoreData/test2-CoreData/main.m:16 </code></pre> <p>All the Core Data setup is from the standard inclusion when I checked "Core Data" on the empty new project.</p> <p>Presumably I'm overreleasing a managed object, but where?</p>
 

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