OK. I've been able to get an opaque background by setting navigationBar.scrollEdgeAppearance to standardAppearance. Nevertheless I still can't understand why some navigation items default to opaque and other transparent.

I can't get the point of transparency on navigation bar. I have some navigation controllers that can be presented over general application view. These navigation controllers contains tableviews. When pushed the navigation bar is transparent. If the tableview is slightly scrolled up, the navigation bar fades to opaque. It fades back to transparent when the tableview is scrolled down again. It looks to me as a bug on navigation bars. Moreover I've not been able to get navigation bar to be opaque, whatever I tried until now.

I'm experiencing this transparency issue on navigationBar. It is not present in all case. Some are always transparent unless one scrolls up the tableview inside, some are randomly ok (opaque) or ko (transparent) with no reliable cause. Calling setContentScrollView on the navigation controller with the contained tableview does not solve the issue