rotate around object when sliding acros the screen

Hi there! Im making a iPhone game but i suck at it and i would like to know how to rotate around an object by sliding acros the screen.
If you’v played “a monster ate my homework” you will understand what im trying to say

type transform.rotate into the script reference in unity and this will give you a detailed instruction on how to do it, then serch input on it as well

I would use transform.RotateAround(). The dox can be found here: RotateAround()