title: Detect if drawing a path is a circle/rectangle in xcode
body: <p>I want to implement a auto complete feature for a drawing app. Once a free hand object is drawn, I want to detect the type of object (circle/rectangle/triangle) and based on the result would want to plot a corresponding object. </p>
  
  <p>I have read up a bit about OpenCV but then I would need to convert the user drawing into an image at real time.  I am recording the number of points plotted/traced by the touch and also generate a <code>UIBeizerPath</code> of the corresponding path. How do I go about to detecting the shape type? </p>