Have you ever tried to use your iPhone or iPad take a picture of a box, a sheet of paper, or something else that’s precisely rectangular, but been annoyed that the image came out skewed because it was difficult to get your camera level?
Fortunately, Apple snuck a camera level in iOS 11, but it requires enabling a seemingly unrelated feature and noticing a subtle new interface element. Here’s how to access it.
https://tidbits.com/2018/04/13/the-hidden-camera-level-in-ios-11/