Large level loading best practices

Hi all,

Sorry if this question has been asked before, but I have looked all over and have not found the answer that I'm looking for.

I'm developing a game for iOS and my levels are quite large. So I was wondering if there is any best practice for loading and unloading parts of a scene as the player moves through it. Occlusion culling is only for rendering, so I need to have a way to enable and disable objects as well. I can come up with a few different methods to do this.. but I wanted to know first:

Is there any best practice or standard already?

Thank you for your time.