I am curious for this as well, for iOS along with Android devices. Recently, I had an issue where my field crews were out collecting features, stopped for lunch and turned of the device, when they turned the device back on, all of the maps through collector were gone, no maps stored on device. I was able to pull the work off of the device through windows explorer in the Arcgis_collector folder, but the data appears to be stored in one file called a GEODATABASE file,which originally I thought this was great but ArcCatalog/ArcMap nor anything will read this file. I'd really like a way to pull this information out without having to send the crews back out to repeat their work. In hindsight it would be wise not to turn off the devices before syncing your edits.
Thanks
Brian
Northeast Ohio Regional Sewer District, Cleveland Ohio