Get the co-ordinates of markup on image in cocoa

Question

I need to get the co-ordinates of markup(it may be circle, rectangle or any shapes) on image in cocoa. It would be starting x,y points when markup starts or the x,y points when markup ends.

Now I am to able to draw a shape on image, but I am unable to get the x,y points of that shape.

   [_imageView setCurrentToolMode: IKToolModeAnnotate];

This line of code I am using to draw a shape.

Can anybody help to solve this problem.