Custom Field Link to Post

Hi Guys,
I did search around for an answer to this but all the solutions seem to be over a year old so I wondered if there was a more up to date technique.

What I’m trying to do is add a custom field for posts that allows me to link to another post. For example, when editing “Hello World” a custom field is available that displays other posts as a dropdown. When I select a post and save Hello World, a link to the post is then shown.
Does anyone know how to do this?
Thanks guys.