Grappling Gun with Aim Assist

I would like to know how to create a Grappling Gun with Aim Assist, similar to the Batman Arkham Grappling Gun.
I’ve no real idea how to start on creating this so I’ll appreciate any Idea here.


I believe this tutorial should help:

My biggest problem is to make it automatically target ledges, even if they’re outside the players view.

So I’ve finally got the time to implement the grappling hook of the tutorial but is there really no one who knows how to create a full auto targeting for it?