Does anyone know if Apple approve apps with a button in a tab bar that just refreshes the current view and not change the actual view?
I don't think so. The Tab Bar is a very well understood metaphor - like tabs in a folio. Using a tab as a button is definitely not expected behavior.
I'd recommend a UINavigationBar
with a button to refresh.
EDIT:
This is a direct quote from Apple's HIG:
Don’t use a tab bar to give users controls that act on elements in the current mode or screen.
If you need to provide controls for your users, use a toolbar instead.