Object dealloc only crashes in iOS 4.3 - iphone

Question

I'm trying to figure out why pushing a viewController in my tableView using didSelectRowAtIndexPath would cause a crash in iOS 4.3, but in iOS 5.0+, it works fine.
It crashes right when I call:
self.customViewController = [[[CustomViewController alloc] initWithNibName:#"CustomViewController"bundle:nil] autorelease];
anytime after the first time the customViewController has been pushed.
Here's my relevant code:
#property (nonatomic, retain) CustomViewController *customViewController;
-(void) dealloc // Dealloc of tableView.
{
[customViewController release];
customViewController = nil;
}
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
self.customViewController = [[[CustomViewController alloc] initWithNibName:#"CustomViewController"bundle:nil] autorelease]; // Release old, allocate new, set it.
[[self navigationController] pushViewController:customViewController animated:YES];
[customViewController release]; // Balance out pushViewController's retain.
}
Thanks.

Answer 1

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
self.customViewController = [[[CustomViewController alloc] initWithNibName:#"CustomViewController"bundle:nil] autorelease];
[[self navigationController] pushViewController:customViewController animated:YES];
[customViewController release]; // Balance out pushViewController's retain. ---->NO
}
The last release is an extra one that is not needed.
You already have done an autorelease on it to have it's retain count down by one.
We will analyse this line
self.customViewController = [[[CustomViewController alloc] initWithNibName:#"CustomViewController"bundle:nil] autorelease];
you create a CustomViewController retain count == 1.
You say autorelease on it so retain count will be 0 later (probably the end of the run loop), but for now it's still 1 that is why you still have access to it, but treat it as 0.
After that you say self.customViewController, that property is retain, so retain count == 1.
And you are taking care of that 1 in your dealloc.
As of your comment :
// Balance out pushViewController's retain.
You don't Balance those, you balance only the one YOU own. If the system make retain on your objects, it will release them when the system don't need them anymore.

Answer 2

Don't release the customViewController. You've already autoreleased it when you assigned it, so you've already given up ownership from the alloc. You don't have to release or autorelease the object again. The navigation controller takes ownership and will relinquish it by itself at the appropriate time.
Also, it's coincidence that you may see it in one version and not another. This is a memory management problem, so any corruption you might see (crashes, etc.) will be dependent on the state of memory on the device whenever you run the app. You may see a crash all the time, never, or only after running Skype but before opening the Photos app.
A good way to look for these is to enable zombies during your debugging sessions. With zombies enabled, objects are never actually released. Instead they are put into a zombie state and if they're ever sent a message again, they will abort the app and show you where the stray message was sent to help you debug your memory issues.