Black smudge under navigation controller when tran

问题:

When I'm tabbing between pages attached to a navigation controller, sometimes there is a black mark under the navigation bar..

any ideas how to remove this?

they're just blank pages.

let vc = self.storyboard!.instantiateViewController(withIdentifier: page)
            self.show(vc, sender: self)

i have tried setting background to white in navigation controller class like some threads recommend which didn't do anything.

回答1:

The "smudge" happens when you transition between a view controller whose edgesForExtendedLayout include .top and one that does not. To avoid it, make sure all your view controllers have the same edgesForExtendedLayout and the same extendedLayoutIncludesOpaqueBars settings.