Core Data deleteObject crashing app with EXC_BAD_ACCESS

I'm loading a User object from my fetchResultsController, getting a bunch of related Sites objects from said User, putting them into an array, sorting, then displaying in a UITableView.

-(void)loadMainUser {

id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:0];

if([sectionInfo numberOfObjects]) {

    NSUInteger indexArr[] = {0,0};
    NSIndexPath *indexSet = [NSIndexPath indexPathWithIndexes:indexArr length:2];
    mainUser = (User *)[self.fetchedResultsController objectAtIndexPath:indexSet];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"siteName" ascending:YES selector:@selector(caseInsensitiveCompare:)];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:&sortDescriptor count:1];

    sortedMsgs = [[mainUser.sitesToUser allObjects] mutableCopy];
    [sortedMsgs sortUsingDescriptors:sortDescriptors];

    [sortDescriptor开发者_运维问答 release];
    [sortDescriptors release];      
}

[self.theTableView reloadData];

}

Now my scenario is I want to delete this User object and related Sites. However whenever I try and save the delete, my application crashes with a EXC_BAD_ACCESS error. Here is my delete code:

-(void)deleteUser {

sortedMsgs = nil;
mainUser = nil;

NSUInteger indexArr[] = {0,0};
NSIndexPath *indexSet = [NSIndexPath indexPathWithIndexes:indexArr length:2];

NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];

[context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexSet]];
// Save the context.

NSError *error = nil;
if (![context save:&error]) {       
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
} else {        
    // do something
}
}

I'm not entirely sure why though... I noticed that my mainUser had a retain count of 3 which I assume is because of the sortedMsgs and UITableView... Is it because my UITableView is still showing the data from effectively the User, and then I delete it? Really confused...

Here's the crash log:

Exception Type:  EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x0000000000000016
Crashed Thread:  0  Dispatch queue: com.apple.main-thread

Application Specific Information:
objc_msgSend() selector name: isTemporaryID
iPhone Simulator 235, iPhone OS 4.2 (iPhone/8C134)

Thread 0 Crashed:  Dispatch queue: com.apple.main-thread
0   libobjc.A.dylib                 0x01613a63 objc_msgSend + 23
1   CoreData                        0x00e20d26 -[NSManagedObjectContext save:] + 566
2   Clicky                          0x00002cfd -[RootViewController deleteUser] + 358 (RootViewController.m:71)
3   UIKit                           0x003eaa6e -[UIApplication sendAction:to:from:forEvent:] + 119
4   UIKit                           0x005f8167 -[UIBarButtonItem(UIInternal) _sendAction:withEvent:] + 156
5   UIKit                           0x003eaa6e -[UIApplication sendAction:to:from:forEvent:] + 119
6   UIKit                           0x004791b5 -[UIControl sendAction:to:forEvent:] + 67

My only guess at this point is that you may be deleting an object that has a required relationship to another object. Check your relationships within the data model?

Totally a hunch.