It turns out I was thinking of the exposure/brightness controll.
Sorry I don't use iOS very often (and very rarely use the camera app.)
I think my point still stands though. The UI is not at all discoverable (and not all that ergonomic either which is why most people might tolerate some lack of discoverability.)
When you tap on your screen, the camera focuses on the point you tapped. It also adjusts the exposure to the point you tapped. And right next to where you tapped, a simple slider with a SUN ICON appears, and you can drag that slider to adjust the exposure.
The fact you don't use iOS and the Camera app, I'm fine with that. But you're telling everyone how bad the iPhone UI is without using it and misleading people about how it works. Not quite fair.
In any case, it's easy to pile on Apple, until you try to do it yourself. Let's see this Android OS match something at least half as usable as what the iPhone UI is. It took Android a decade to get there.
Sorry I don't use iOS very often (and very rarely use the camera app.)
I think my point still stands though. The UI is not at all discoverable (and not all that ergonomic either which is why most people might tolerate some lack of discoverability.)