如何将角半径添加到UIBezier路径弧

I am creating an arc using UIBezierPath arc convenience method. I want the ends of the arc to be rounded off - see attached sketch for exact requirement! The cornerRadius option used in the roundedRect version isn't available for the arc method. Anyone got an ideas on how to achieve this? Thanks in advance. (This is different to previously asked question in that it provides exact requirement)I am creating an arc using UIBezierPath arc con