ViewController Was Deallocated Unexpectedly
<p>I have a very strange problem and I hope I can get some help. </p>

<p>I have ExpenseListViewController that has its fetechResultController, and once a row is selected from the tableview, the code push detailViewController to the stack.</p>

<pre><code>  - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

    // Create and push a detail view controller.
    ExpenseDetailVeiwController *detailViewController = [[ExpenseDetailVeiwController alloc] initWithStyle:UITableViewStyleGrouped];
    selectedExpense = (Expense *)[[self fetchedResultsController] objectAtIndexPath:indexPath];
    // Pass the selected expense to the new view controller.
    detailViewController.expense = selectedExpense;
    detailViewController.delegate=self;
    [self.navigationController pushViewController:detailViewController animated:YES];
    [detailViewController release];
}
</code></pre>

<p>In the detailViewController I save the context, and the callbacks of the fetchResultController on the ExpenseListViewController get called, but sometimes, not always, the listController had been deallocated.</p>

<p>See error message on the console:</p>

<pre><code>    2010-07-15 18:04:50.404 FunMobile[6396:207] *** -[ExpenseListViewController controllerWillChangeContent:]: message sent to deallocated instance 0x3bc34e0
(gdb) continue
2010-07-15 18:04:52.188 FunMobile[6396:207] *** NSInvocation: warning: object 0x3bc34e0 of class '_NSZombie_ExpenseListViewController' does not implement methodSignatureForSelector: -- trouble ahead
2010-07-15 18:04:52.189 FunMobile[6396:207] *** NSInvocation: warning: object 0x3bc34e0 of class '_NSZombie_ExpenseListViewController' does not implement doesNotRecognizeSelector: -- abort
</code></pre>

<p>I thought the viewController in this case should only be dealloced if it is got popped off the stack, what might be wrong here? I set the breakpoint at the dealloc method of the ExpenseListViewController, it is never called, when this error happens. </p>

<p>This problem happens in both OS 3.1.3 and OS 4.0
Thanks in advance in your help.</p>
