How to hide the last active feature on facebook for iPhone?

So I'm pretty much trying to hide from everyone but I don't know how to do it. I still want to be able to look at my newsfeed and stuff but I don't want people to be able to see when I was last active or whether or not I'm online.

Trying to hide from everyone on facebook is nearly impossible - you can disable your chat, but as soon as you like or comment on something, anyone watching for your activity will be able to see it, and there's no way to just turn that feature off, since the whole point of facebook is sharing your activities, not hiding from everyone