There is an iPad version of Scrivener in the works, but it looks like it will be a while before we see it. Until we do, here are your options for working on your writing project when you’re away from your desk. One caution . . . always backup your project before exporting or importing.
As you see here, there is a Sync command located under the File menu. In this example, I’m synching my project to Simplenote. The Simplenote [iOS - free and $20/year] service is a cloud-based notebook and offers both a free and premium service with a very nice iPad app. When you sync all or part of your project to Simplenote, it exports the manuscript items as text files which you can then edit online or in the Simplenote app.
In this case the use of the word “sync” as a Scrivener command is a bit misleading. You don’t just sync to Simplenote, make some edits then sync back to Scrivener. Once you’ve finished editing on your mobile device, you’ll need to import that text file back into Scrivener.
One of my favorite iPad text editors is Elements for Dropbox [iOS - $4.99] because of its support for markdown. [For more information on markdown, see Markdown - an archival standard for digital documents?] It can also be used to edit your project on the go. In this case, you will “sync” your Scrivener project with an external folder – only this folder will be the Elements folder within your virtual Dropbox folder. Once again, those updated text files will need to be imported back to Scrivener.
While Simplenote offers more options for editing whenever and wherever using either a mobile app or the platform’s Web interface, I find the importing effort more straightforward when pulling in files from a Dropbox folder. That being said, I have no problem taking advantage of whichever option is available in any given situation.
If you are like me and find outlines useful to help plan and organize projects, the Cloud Outliner app [iOS - $4.99 and Mac - $9.99] could be quite useful. There’s also a Lite version of the iOS app if you’d like to take a test drive first. This app supports OPML (Outline Processing Markup Language) a format standard for outlines. Scrivener supports importing OPML files. I’ve gotten into the habit of creating a folder in my Binder just to keep the outlines (yes, plural) I create for a project. It’s part of the “working” files – not part of the manuscript itself.
In the example below, you see a scene from my Future of Memories (FoM) project that has been exported to my iPad using Simplenote.

Scrivener scenes exported to Simplenote.
Here’s an example of the same scene as it appears in the Elements app.

A scene displayed using Elements for Dropbox.
And an outline in my Cloud Outliner app.

Cloud Outliner on iPad.
To import this outline into a Scrivener project, I first used the Cloud Outliner app’s File > Export command to export the selected outline to an OPML file. In Scrivener, I select the Outlines item in the Binder and then use Scrivener’s File > Import > Files command to import the OPML file I just created. As you can see below, the file is delivered to Scrivener with all the outline levels of the original file.

OPML outline file imported to Scrivener.
I don’t attempt to export an entire project to my iPad, but having a section with me at an given time, gives me something to work on when I have a few minutes. Like many others, I look forward to the day I can carry a mobile version of Scrivener with me but until then, I’m make do with what I’ve got. The iPad apps discussed here have uses other than just their Scrivener capabilities and are put to use for many purposes so they were already part of my mobile workspace.