Change width of a popup button programmatically

I have a popup button that I want to shrink the width under certain circumstances. After googling for an hour I can’t seem to find a good example of how to do this. Is such a thing possible… and easy?

Create a button variable and connect via IB

aButton
aButton.width = 80

aButton’s setWidth:80

Thanks. However:

aButton's setWidth:80

Returns: Expected end of line, etc. but found unknown token. (-2741)

Assuming you’re not using autolayout, you can use either setFrame: or setFrameSize:.

So I was wrong. Shane’s answer below will do it.
You may have to get the current height via accessing the frame size first
Unless you know the height. Which you could also reference from IB ruler / size tab.