如何在iphone上做一个闪烁(或闪烁)的光标?

I'm trying to create a custom "blinking cursor" in UIKit, I've tried as shown below, having 2 functions that basically keep calling each other until the cursor is hidden. But this leads to a nice infinite recursion... for some reason the functions call each other right away, not each half-second as expected.I'm trying to create a custom "blinking cursor"