Passing a seed from a game to iOS via facebook

Hi,
We are making an app game & want players to be able to finish a game & then be able to challenge their friends via facebook to beat them on the exact same game boards. We are using deep linking & it is working on Android but on iOS the best we have been able to achieve is getting the game to open to the main menu. Has anyone had any luck getting this kind of thing working on iOS that is willing to share the secret?

thanks

Sean