The free i-FlashDrive HD app runs on your iOS device and serves as a gatekeeper between this device and the files stored on it. The device comes with a pile of files of different types preloaded so that you can easily see how the files are visible on your Mac or PC and your iOS device. For example, here's what I see in Mac OS X Mountain Lion:
When I plug the i-FlashDrive into my iPhone 5, fire up the app, and tap on "External Storage", I see this:
The i-FlashDrive HD supports a number of file types; the above image shows .jpg, .xls, .pdf, MP4, and MP3 files. There are actually 33 supported types from .aac to .xlsx, with Numbers, Keynote and Pages thrown in for good measure.
In addition to this file manager, the i-FlashDrive HD app has more functionality. It also acts as a backup for your contacts file, providing a one-tap solution to copy a clean version of the file to the flash drive in case iCloud decides to erase or modify your contacts. Restoring the file is also a one-tap process. Since the contacts information is stored on the i-FlashDrive HD, you can move it to your Mac or PC for safekeeping.
There's also Dropbox functionality built into the i-FlashDrive HD app. Let's say that I want to copy that contacts backup to my Dropbox account. I simply tap on edit, select the backup folder, tap the Move button that appears at the bottom of the iPhone display, and then select the folder on Dropbox where I want to copy the file.
If you happen to want to move items to Google Drive, that's not a problem either, although the process is a bit different. Since you can view supported files in the app, opening them not only shows you what's in the file, but also reveals a share button. Tap that to open the file in Google Drive (using the iOS Google Drive app), or any other app that supports that file type. In the case of Google Drive, you're asked if you want to upload the file to that service.
One of the other functions that the i-FlashDrive HD provides is that of added storage for your iOS device. Instead of taking up loads of space on your iPhone or iPad with big video files, you can store them on the flash drive instead. I copied a number of 1.0 - 1.5 GB video files from my iMac to the drive, unplugged the i-FlashDrive from the Mac, then plugged it into my iPhone. Opening the file on the flash drive started the playback. What a great way of storing a library of movies without filling your iPad or iPhone!
Speaking of libraries, this is a wonderful way to back up photos from your iPhone or iPad as well. When I'm on vacation trips, I often take photos not only with my DSLR, but also with my iPhone. The i-FlashDrive HD provides a conduit to back up those photos on my Mac quickly.
But wait, there's more! There's also a voice recorder as part of the app. Once again, this allows you to record meetings or long lectures to the flash drive instead of your iPhone's internal storage, and makes for extremely easy syncing to your Mac.
I scoffed when I first saw this little device, thinking that it was yet another great idea that wouldn't work. But the Taiwanese company that manufactures this device really has a great idea and has done a wonderful job of implementing it.
Can be used with almost any modern, updated iOS device
Makes transfer of documents and files between Mac/PC and iOS device a snap
Contacts backup feature is useful
Supports a huge number of file formats
Free app is surprisingly bug-free
Availability of the device in the US may be limited (via Amazon)
Pricing is a little ridiculous, considering that a 16 GB flash drive is available for less than $10 yet PhotoFast charges $150 for the same capacity.
Who is it for?
Anyone who wants a way to store a vast number of documents, video files, or photos for viewing on an iOS device but doesn't want to fill that device's internal storage. Also excellent for anyone who needs to move files between iOS devices and Mac/PC on a regular basis.