How do I build Navigation locks and floats to the bottom edge of the screen?

I would like to build a custom navi bar using view, touchable and custom icon images. Two things I need to accomplish. First, the navi bar has to lock in place, I guess I can achieve this by absolute positioning? Second, the navi bar needs to float on top of everything else.
It seems  the FAB Fixed component does what I want so worst case I can customize and use it FAB Fixed instead of view?