I’m looking for an iOS app with spell-check that will allow me to edit Word documents and sync them with Dropbox.
From reviews I’ve read neither Quick Office nor Documents to Go offer this feature.
Does such an app exist?
If I am right you are asking about the red squiggly lines that appear under mis-spelt words?
The spell check is a native feature within iOS, rather than the app. So if you type in the app you will get the auto correct.
You can use Pages to spell check as this has the red lines but you can't put back into drop box.
QuickOffice does sync with Dropbox, but doesn't spell check, (a feature which may be added soon) Documents to Go only offers dropbox sync with it's premium version which was misled by it's iTunes description.
iWork on the iOS does use the system-level spellcheck. It is not a full spellcheck system, but it is still quite good.
If you need to sync to DropBox, check out DropDAV. It adds a webDAV access to DropBox, which can then be accessed via iWork on iOS.
You get OneDrive with your O365 subscription needed to edit documents on the iPad and of course Dropbox file sync with iOS 11 works quite well, too.