Purpose of UIControlStateSelected

Question

The three other UIControlStates are clear to me, but I cannot understand the purpose of UIControlStateSelected. What/when does a UIControl subclass enter this state?

Answer 1

In the instance that a button, etc. is selected or pressed. A lot of people use that particular one to change images on the object to show a selected state for the brief moment when it is selected.

I have also used it in tables to make it easier to re-use cells by checking for selected states and updating the table cell based on if it's selected or not.