The app conducts the search locally, rather than using the Cloud.
“Both Google and Apple’s services use ‘computer vision’ to detect what’s in photos. But on the iPhone it’s incredibly easy to pick a subject, let’s say ‘cats’ and search your photo library for images that feature a cat,” Fortune reported on Wednesday.
To save you on battery, iOS only does this when the phone is charging. Whenever you capture a new image, Apple’s Image Signal Processor is able to detect objects and people, and will then look them up against its inbuilt database.
To try this hidden feature, open the Photos app and tap on the search magnifying glass. Users can tell Apple Photos who appears in your images and it should then be able to look and identify those people again.