Popovers cannot be presented from a view which does not have a window

Question

What does this error indicate:

\"Popovers cannot be presented from a view which does not have a window.\"

Answer 1

I had the same error message as the OP, in a very similar situation to that reported by TPoschel, except I had a split view controller with an embedded tab bar controller in the detail pane, and a navigation controller within this. The bar button item is added as the navigation bar leftBarButtonItem.

Only on iOS5.0 (not 5.1) does it seem to require you invalidate the bar button item on the tab bar you are leaving by setting it to nil. Before then adding the bar button to the navigation bar on the tab you are going to.

If I don't do that, from debugging my own code, the window property of the bar button item stays set to nil, and causes the exception, on returning to a screen you'd previously been to. I'm guessing as a side effect of setting the leftBarButtonItem in the navigation item, it goes off and sets the frame. But it doesn't seem to bother unless the button is different from what is currently set there. Hence, the need to set it to nil when leaving a tab, even though it is technically the same button that's being passed around.

I would upvote TPoschel's answer, except SO won't let me.