Before iOS 12, you’d tap the camera button in a Messages chat in order to share either a brand-new photo or a photo that had already been taken. In iOS 12, Apple changed things so tapping the camera button only lets you take a fresh photo. To find and send a photo that’s already in Photos, use the Photos mini-app in Messages. If necessary, tap the Apps button to the left of the message field to show the Messages apps, and then tap the Photos button to see a list of recent photos. Tap one or more to add them to the message, and you’re ready to send!
Check out another iOS 12 tip here, and learn how to avoid missed alerts!