IPhone EXC_BAD_ACCESS when calling [super dealloc] on user UIViewController

Question

I am at a loss! This is one of those nasty mistakes that happen only under certain conditions, but I cannot directly relate the conditions and results.

My application has paged UIScrollView, where each pageview comes from MyViewController, a subclass of UITableViewController. To minimize memory usage, I unload controllers that are currently not visible. Here is my "cleanup" method:

- (void) cleanViewControllers:(BOOL)all {

    if (all) { 
    // called if some major changes occurred and ALL controllers need to be cleared

        for (NSInteger i = 0; i < [viewControllers count]; i++)
            [viewControllers replaceObjectAtIndex:i withObject:[NSNull null]];
    }
    else if ([viewControllers count] > 2) {
    // called if only the nearest, no longer visible controller need to be cleared
        NSInteger i = pageControl.currentPage - 2;
        if (i > -1) [viewControllers replaceObjectAtIndex:i withObject:[NSNull null]];
        i = pageControl.currentPage + 2;
        if (i < [viewControllers count]) [viewControllers replaceObjectAtIndex:i withObject:[NSNull null]];
    }
}

This is the line that causes the application to crash:

viewControllers replaceObjectAtIndex:i withObject:[NSNull null]];

viewControllers is an NSMutableArray containing objects of type MyViewController. MyViewController has no custom properties, and its dealloc method contains nothing but a call to [super dealloc].

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Answer 1

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Answer 2

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UIBarButtonItem* timeLabel = [[UIBarButtonItem alloc] initWithTitle:@"time" style:UIBarButtonItemStylePlain target:nil action:nil];

NSArray *items = [NSArray arrayWithObjects: timeLabel, nil];

self.toolbarItems = items;

:

[timeLabel release];

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Answer 3

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Answer 4

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