I don't think you really understand how iOS works. iOS uses points as its units, not pixels. One point on a retina display is two physical pixels. One point on

I don't think you really understand how iOS works. iOS uses points as its units, not pixels. One point on a retina display is two physical pixels. One point on a non-retina display is one physical pixel. To create a one pixel thick line on a retina display, it must be half a point thick.