Google announced on there Official Blog new mobile apps for Docs, Sheets and Slides.
These new app’s will allow editing of Google Drive documents offline and without internet access, unlike the Google Drive app which requires internet access for editing.
The apps are in Self Service for iPhone’s and iPad’s, but here are the direct App Store links:
Slides was just released with updates for Docs & Sheets allowing them all to open and edit Microsoft Office files. Slides will be added to Self Service as soon as possible.
