Why close the session on app exit? (ios)

[Tomobodo]

Hello, i'm using your extension for some mobile game (ios/android) and we want to use facebook so that the user can publish his score ect ect. Everything works nicely except that the facebook session is lost between the app launches on iOs. I never coded in objective-c before but i found that the session is closed on the willTerminate handler. I just commented it and now the app have the behaviour i'm expecting. I just wanted to ask why close the session on iOs on app exit and not on android ? Am I introducing some potential bug by doing so ?

Thank you !