title: How can I build a transparent view with shadow outside in iOS?
body: <p>I want to build a totally transparent view, the backgroundColor maybe clearColor. Inside this view I want to put a small image. And in the four sides of this transparent view, I want to see the effect of shadow. The shadow must be totally outside the view. I know that I must override the drawRect method in UIView, but don't know how to do this.</p>