UINavigationController crashes after pushing 3 views onto stack

I have a navigation controller, which has the following structure:

Category
    Item
        Item Detail

I can choose a category, and then choose an item to see 开发者_开发问答its details. I can do this twice, i.e. go Back to the list of items and select another item. If i try this a third time, the app crashes, I get objc_msgSend in stack but thats all. But, instead of choosing another item, i go to the list of categories, and choose a different category, I can select two items in that category, before it crashes also.

What would be causing this?

Thanks

It may due to the way you declare private variable. The answer is embedded in my question posting here: UINavigationController crash because of pushing and poping UIViewControllers

Solved. I was overreleasing a variable. Used Allocations in Instruments with the record reference counts and nszombie options switched on to track it down.