I want to check for any update to the kerning dictionary of a font and do stuff accordingly.
I’m currently using the
UPDATEINTERFACE callback, and it works as it should, but because I only need to check for kerning changes and I don’t want my callback function triggered all the time, I’m guessing there’s a better way to do it.
I’ve seen the
addObserver_forObservableKeyPath_ methods , but not quite sure of how to use these, what arguments they take and how to define the callback for them.
Any help on how to get started?