The wheel is of course a riff on those found on cameras from cheap analogue snappers (for selecting modes) through to full-on SLRs, and it works wonderfully. You drag across the wheel to select a tool, tap to confirm, and drag again to choose an option. This provides fast, straightforward access to your camera type, a grid and spirit level, flash and format settings, and filters.
Two large buttons flank the shutter button, for quickly getting to manual exposure and focus levels. When either of those is activated, the wheel transforms into a series of tick marks, enabling you to make subtle adjustments with a single digit. When focussing, subtle peaking further helps with precision.
Even on a surfboard-sized iPhone 8 Plus, you can control everything with a single thumb; almost as importantly, using the interface is enjoyable, with the phone sending haptic feedback your way as you choose settings, or when the spirit level responds whenever your shot is aligned perfectly.