Black smudge under navigation controller when transitioning

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.

回答2:

for me, It happens when I use ToolBar from libraries. fix by using ToolBar from the navigation controller itself by toggle "Shows Toolbar" in Navigation Controller's Attribute Inspector

来源：https://stackoverflow.com/questions/41842359/black-smudge-under-navigation-controller-when-transitioning