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

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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

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