[sp332]

Most of the touchscreen functions are not discoverable. Pinch-to-zoom, long-press, swiping with multiple fingers, etc. It's very easy to do though, not what I would call a power-user thing. Remember there is only one physical button on the front of the device, and this is one of the things that it does.

[DanBC]

Yes, I misuse "power user" to mean "someone who reads the fine manual" or "someone who does a websearch to learn about nice features".

[sp332]

At least for some features like pinch-to-zoom they included very clear examples in the massive ad campaigns. I don't remember seeing this feature in an ad but it wouldn't surprise me. At least it's on this page https://www.apple.com/iphone-6/design/