How to get the full path to a file on iOS 8?
Getting the 'full path' to a file on a non-jailbroken device is not useful as you can't access the file directly anyway. Generally, this is not possible, although you may be able to infer the location of a specific file.

For what it's worth, the full path to an image in your camera roll is:

/var/mobile/Media/DCIM/###APPLE/IMG_####.png