Thanks for the suggestions Nandit and Ronald.
Unfortunately neither of the suggestions are ideal - but good ideas.
The users really like taking photos through the app, seeing them in a gallery and then submitting them all at once. I don't want to force them to have to take the photos outside of the app and then come in to the app and attach them. Some users are not that technical so could get confusing for them.
And my preference is to do a single write rather than multiple updates to the list as they take their photos. Also because they get to check the final set of photos before saving.
But you have given me an idea - perhaps I could do a save to a temporary sharepoint list as they take them. Then remove the temporary list photos once they are submitted properly as a final write. Bit complicated plus many more writes/deletes and might have a performance impact.
I suppose I was just hoping there might be some new app functionality allowing one to save to the camera roll at the same time as saving to a collection. But perhaps that is just wishful thinking.
