When I analyzed the file system extraction with the Physical Analyzer software by UFED I got the same results as the Oxygen Forensic Suite. I was not surprised by this. Here is what the file system looked like for the Snapchat app.
The Snapchat app contained a Documents folder and a Library folder. In the Documents folder was a plist file called user.plist. In the Library folder there was a Preferences folder that contained a plist file called com.toyopagroup.picaboo.plist. These two plist files were the same plist files found by the Oxygen Forensic Suite.
I also wanted to try the mobile forensics tool XRY. I used the XRY Complete, but unfortunately it could not do a physical extraction of the iPhone 4S. So, I did a logical extraction of the phone.
In the Documents section of the extraction I was able to locate the two plists that were found with the Oxygen Forensic Suite and the UFED Cellebrite.
The next step I will take in this project is to jailbreak the iPhone 4S so I can then create a physical dd image of the phone, and also take a memory dump.