CoolDown Animation on the GUI

I want to make an animation on the GUI acording at the state of the CD, the animation must be a circular “Radar Style” animation, its mean, like the Classical famous count down before the cinemas movie starts.
It’s similar to World of Warcraft ability CD animation con the GUI.

You can create a black square and cut it as the steps of the cooldown,
then create an animation of it in unity (play with the square opacity for best result).
Active the animation when the skill start cooldown, and play with the animation speed according to the skill cooldown.