Figuring out Mafia/Pet shop games work

[zardon]

I've been playing a few pet shop games, and mafia games; and have noticed some traits which seem similar;

1. They are reliant upon time.
2. In mafia games you can add 'friends' via some kind of 6 or 9 digit code.

My questions

1. Are they using Local notifications for the time events? Or do they use something else? Would they store the times in core data or a sqlite database?

2. How does the friend system work?

My best guess is that the friend system relies on your device id, and 'registering' you automatically when you first start the game; and then using an API to detect who you are 'friends' are.

But, is this right?