I used this solution to add navigation bar to a tabbarcontroller : How to use Navigation Controller inside of UITabBarController with Storyboard on Swift
But I find a problem, for exemple, I embed a navigation in the view A of tabbarcontroller, after I use self.navigationController!.pushViewController to pass view A to view B, after there is a back button with a arrow in view B. The problem is When I click the back button, the animation from view B to view A disappear... view B pass view A sudenlly, the animation is view B pass view A slowly, but the animation doesn't work, why? Thank you