Calculate points for borders inside and outside of a polygon

Question

In my code I get some set of points that define a simple polygon. I need to draw the polygon itself, as well as a border inside and outside of it

If it was a rectangle, I could simply use CGRectInset() on iOS. However, it isn't a rectangle.

So I need an algorithm that provides me the inner and outer borders from a simple polygon.

Answer 1

Check out CGPathCreateCopyByStrokingPath.