Migrating an old app to iOS8, popovers were going mad.
Weird problem with the "popover dimming view" -> I mean the darkish effect on background views provided by the system when you fire a presentPopoverFromRect.
I happen to have the dimming view in the wrong orientation. When I am in landscape, the dimming view is in portrait (you could see the edges in the middle of the screen).
The problem was related to the main xib.
For some reasons the Window was created within a xib. Couldn't find anything wrong with it but I removed the window, created it by code, added the view controller manually, and all went back to normal. I suspected some default settings to be overridden by IB, went back to the faulty window, couldn't find anything wrong.
So, if this happens to you : check you window and/or try to add your window by code.