Alright till they release a better or correct way to get xfire to detect Battle Field 3

Find your xfire_games.ini

Search in the INI for BattleField 3 replace

[6894]
LongName=Battlefield 3
ShortName=bf3
LauncherDirKey=HKEY_LOCAL_MACHINE\SOFTWARE\Electronic Arts\71171\Install dir
LauncherUrl=http://battlelog.battlefield.com/bf3/
DetectExe=bf3.exe
Launch=%UA_LAUNCHER_URL% %UA_LAUNCHER_EXTRA_ARGS% %UA_LAUNCHER_NETWORK_ARGS%
RunElevated=1


With

[6894]
LongName=Battlefield 3
ShortName=bf3
LauncherUrl=http://battlelog.battlefield.com/bf3/
DetectExe=bf3.exe
Launch=%UA_LAUNCHER_URL% %UA_LAUNCHER_EXTRA_ARGS% %UA_LAUNCHER_NETWORK_ARGS%

That will get BattleField 3 to detect on xfire however broadcasting and ingame stuff isn't working but if you want hours thats how you get it to work

You will need to save the INI and then close xfire then restart xfire
go to the Detect games and where is shows the games on the left look in there for BattleField 3 and click on it then go to the right side of that where it shows select games and Manual Detect from there click the browse button and locate your bf3.exe on Windows 7 its located in

C:\Program Files\Origin Games\Battlefield 3

Or

C:\Program Files (x86)\Origin Games\Battlefield 3

Credits to : zarabyte on xfire