title: Redrawing a UIView with animation
body: <p>I am a novice ios programmer &amp; I am doing my first ios project. In my project I have several <code>UIView</code> and <code>UIViewController</code>. In each view I have overriden <code>drawRect</code> method and drawn several circles. In one my view  I need to draw a rectangle and when I touch it, it would draw another 3 rectangles beneath it with animation. I was wondering what would be the best way to do it! I was thinking to redraw the view after touch by calling <code>setNeedsDisplay</code> and draw the other three rectangles with animation. How can I achieve this and what else method would be best to perform this particular thing with animation?</p>