https://www.theverge.com/2017/12/20/16798388/pokemon-go-niantic-apple-iphone-ios-arkit-augmented-reality-ar-plus

Niantic Labs, the developer of mobile augment reality hit Pokémon Go, today announced that an update of its iOS version out later this week will optimize the game with Apple’s ARKit framework. The framework, part of iOS 11, will allow the developer to add an all-new AR+ mode with far more advanced augmented reality features.

ARKit lets iOS developers take unique advantage of iPhone and iPad hardware and software advancements to intelligently place virtual objects in the real world. Niantic is using it to now fix pokémon in the camera viewfinder with higher accuracy and true-to-life size ratios, based on data about the creatures culled from the game series’ database. Prior to AR+, Pokémon Go would use rough approximations of where objects were to try and place the pokémon in your environment, but it was mostly a clunky workaround that functioned mostly as a novelty feature.