Coming straight from the Pokémon GO blog:

Trainers, Get ready for even more realistic Pokémon encounters: AR+ is coming to Pokémon GO! AR+ leverages Apple’s ARKit framework to build on the AR work already implemented in Pokémon GO. Soon, Trainers around the world running iOS 11 on iPhone 6s and newer models can experience AR+ in Pokémon GO.

I think nearly everyone has seen the incredible ARKit in action, and it’s going to add a lot of benefits to Pokémon GO:

• Everything is based upon fixed locations, so the Pokémon should stick to their position and not move around everywhere.
• The scale will be much more accurate, so a Pikachu will not be the same size as Gyarados.
• Pokémon will now have a sense of awareness, meaning you may need to sneak around, otherwise you could scare it away. That’s certainly one great addition that is enabled by ARKit.
• Because of the real world positioning, it will enable them to place Pokémon in more suitable locations, such as a Snorlax blocking your path!

I can’t wait to start playing it again!

Read the full announcement.
Download Pokémon GO for iOS.