MKAnnotation vs MKOverlay; centering crosshairs

Newbie best practices question here; I'll write the code if someone can give me a开发者_StackOverflow社区 gentle push in the right direction...

On my MKMapView, I would like a cross-hairs or some other indication of where the center of the map is as the user scrolls and zooms. Should this best be achieved as an annotation I keep removing and adding, or as an overlay that I keep resizing and repositioning? Or a third solution? The goal here is best user experience...

Your thoughts?

What do you mean by center of the map? The center of the world or the center of the screen? If it's at a fixed location on the world, use an annotation. If it is fixed on screen set up a UIView that hovers over your MKMapview and passes any touch events through to the views below