iPhone 4 space used but not allocated I've been using the (iPhone) app Flash Drive, which you can use to start a http:// server on your phone and connect to it using Finder and transfer files. I recently transferred a .mkv file of over 1gig to my phone. It took a solid 5mins to complete, and then after it said done, the app's size showed up as zero KB on the phone. Even through Finder, the file shows up as zero KB, so I deleted the files individually via Finder. Now, the space is allocated on my phone, but the files don't show up any where. I connected using my FTP/WebDAV client to see if there are any hidden files (.XXX) taking up space, but nothing, just the same files I see through the app's interface.

Anyone have an idea how I can get the unallocated space back? I restarted my phone using the regular method, but still the space is taken up and I'm deadsure that I didn't put anything else on my phone which could have taken up the space except the two separate incidents with the .mkv file.

Thanks in advance.
I don't know the specifics of that particular App, but allocated space for 3rd party applications in the iPhone is restricted to themselves. That means that Application 1 cannot read Application 2 data. This security measure greatly limits the ways we have to share data among applications (and has made Dropbox very popular).

Given the above, it's very likely that the app Flash Drive uses its own space for storing the file(s) you upload (because it doesn't really have any other place to put it unless you jailbreak your device).

With that said, deleting the application from the phone and (just in case) fully restarting it, should recover the space. You can later re-copy the application to your phone by connecting it to iTunes again.

In order to delete it, make sure it's closed (i.e. not running), touch and hold the App's icon until it wiggles and touch the (X) on the corner of its icon. It will ask you if you want to delete the App and the Data (or warn you about it). Go ahead. Then shutdown your phone and restart it again.