In a tweet shared last night, Google Photos announced that Lens was coming to iPhones and iPads, saying "Starting today and rolling out over the next week, those of you on iOS can try the preview of Google Lens to quickly take action from a photo or discover more about the world around you. Make sure you have the latest version (3.15) of the app."
After you download Google Photos (available here), you'll find Lens by opening a photo in the app, and then tapping on the Lens button, which is on the bottom of the screen, between the buttons for delete and settings.
Once you've got Lens, you'll be able to use its tricks to learn more about the buildings, plants, works of art and other objects around you. This includes everything from movie posters to album covers. Google Lens can also identify business cards and offer to create a new contact from that information.
Of course, since Google Photos is "rolling out" Lens over the next week, you may not see the its icon in your photos. Instead, you might see the Information 'i' that shows up on my device when I try to access Lens.
To make sure you're up to date, open the App Store and tap Updates, and check if Google Photos has an available update. To see if you're on version 3.15 of Google Photos, open the app, tap the menu bar in the top left corner, tap the settings icon and then tap About Google Photos, which is at the very bottom of the screen.