I don't want a certain fb friend to see when I comment on other peoples activity.but im happy for them to see my statuses. Also people know when im on FB through chat when im on my iphone or ipad. I want to look offline, yet still be able to reply to any messages.this is not a problem when I use my laptop and I can see an option to turn chat on.
См. статью: How to stop someone seeing my comments on Facebook?