title: Drawing with drawRect method - Cocoa
body: <p>I've been looking for solutions but can't figure out if it is possible to do the following:</p>
  
  <p>I have a drawRect method, what i want to do is to add a graphic element (such as rects and lines) to the current view without refreshing it. I used to call setNeedsDisplay but this method is actually deleting myView an re-drawing it from 0.. Any suggestion to keep the old one and add new content ?</p>
  
  <p>Thank</p>