Is it possible to view the contents of files in the iOS Application sandbox while debugging?
Updated answer for Xcode 6:
The Devices tab now has it's own window (Window -> Devices). Find your Device, then your App. There is no 'download' button (unless the log window is visible... then the Download icon there actually saves the Log).
If you DOUBLE-CLICK on your app, a new window will become visible that shows a read-only, non-interactive representation of that app's sandbox.
To download the app container, select an app, click the "Gear" and "Download Container." It'll take a bit of a while, during which time there is no indication of the progress; but a Finder window will appear, showing with your .xcappdata file. You can also "Replace Container" which looks cool and exciting.