Listen for Layer Changes?

Hi

I am looking at subscribing to network events and working out event ids and things and so far haven't been able to work out this. Fairly simple question, hopefully the answer is just as simple.

Can I subscribe to an event which lets lets me listen for any layer changes (in my iOS app)? The docs suggest any actionable event can be listened for, but I am yet to work out how to do this.

Thanks.