Your screenshots are showing a tab bar. hidesBottomBarWhenPushed is for hiding a toolbar.
From the documentation for hidesBottomBarWhenPushed:
A view controller added as a child of a navigation controller can display an optional toolbar at the bottom of the screen. The value of this property on the topmost view controller determines whether the toolbar is visible. If the value of this property is true, the toolbar is hidden. If the value of this property is false, the bar is visible.
Topic:
UI Frameworks
SubTopic:
UIKit