Strange delay with Navigation Controller behaviour

I have the following set up in a navigation controller.

The root is a list of categories (banks, hotels etc) and each category has a child view below it containing a table view of items (Bank A, Bank B etc). When i select 'Banks' i see my banks (list coming from from web service), but then i go up one level to my root, and select 'Hotels', when the view loads (from web service), i still see my banks, for about 1 second, before the view is updated with the list of hotels.

How can i stop the previous category's list showing up when i choose a different开发者_JS百科 category?

Thanks

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Clear the array first before you load the view, try also getting views to reload