How to check if Option key is down when user clicks a NSButton

Question

I have a few checkboxes along with textfields on a NSPanel that opens to get user parameters. As an option, I'd like the user to be able to set/unset all the checkboxes on the panel by holding the option key when they press any of the checkboxes.

I'm not sure where/how to check what the key board is doing when the user clicks the button.

Answer 1

check [NSEvent modifierFlags]...

if ([NSEvent modifierFlags ] & NSAlternateKeyMask)
{
    //do something
}