If you just want to jot down notes, ideas you get, new pieces of text, etc, and not edit what you have already written, there is another simple way:
Drafts 4. agiletortoise.com/drafts/
It’s a quick app for writing stuff, and there are numerous “actions” available to send the content to other apps: drafts4-actions.agiletortoise.com
Among the actions you have ‘Save to Dropbox’, which you can easily edit to save the content to the Scratch Pad in Scrivener, provided the Scratch Pad is located in Dropbox. I use it a lot. When I open Scrivener, I open the Scratch Pad and simple add the new text to the project, or put it in Research, etc. Very convenient.
If you want to edit what you’ve already written in Scrivener, another alternative is Index Card.
Moving the text back and forth between Mac-Scrivener and iPad-Index Card require a few more steps when you set it up (very well described in the Scrivener manual). The beauty of Index Card is that you get the whole Cork Board view of your Scrivener project in Index Card, and besides editing you can move things around in the iPad app and then update the Scrivener project with the edited outline when you return to your Mac.
Right now I think that is as close as you get to an iOS version of Scrivener. The only thing that doesn’t work is rich text formatting. Index Card can handle .rtf format, but Scrivener currently sync using the format of the previous version of IC, which couldn’t handle .rtf format.
(there is a work around, as IC can export in .scriv format, so you could edit in IC, export in .scriv and then reopen as a new project in Scrivener; but then you would have to set up the sync again in the new Scrivener project, each time you do this; a bit cumbersome, but possible)
I don’t usually use any formatting while writing in Scrivener so to me it works okay, as long as I remember to ‘Sync with Index Card for iPad’ before closing Scrivener.