https://www.theverge.com/2018/9/17/17870956/ios-12-tenor-update-camera-stickers

Tenor, the GIF platform acquired by Google earlier this year, has launched an integration with the iOS 12 camera platform that allows you to search for and add stickers to photos and videos within the Messages app. It’s a lot like an Instagram story or AR stickers from Giphy.

The updated function allows for users to search stickers by keyword or within already-created “expression categories” like “kiss,” “mindblown,” or “hello.” Once found, stickers can be dragged to the live camera view. Add as many stickers onto the live camera view as you’d like to decorate it before sending.