I was wondering how can I play clash of clans off-line on the iPod touch, because I'd seen some of my friends playing it without a Internet connection and I believe they have android devices. And if it helps I also have game center account.
Let's get this established first, the Client is your device where you are accessing the Server that Supercell is hosting. So your device, (the client) is always talking to the server.
Your idea makes it so the client is operating by itself, and as you know, if you lose connection your client is by itself. And when you get connection again the client re-syncs with the server. This is why when you lose connection during a raid yet you are still continuing the raid, the part you continued never happened according to the server, so when your client re-syncs with the server, your continued part of the raid never existed. So the server is what is making all the data possible.
With your way... it makes it so the client is controlling the situation. So when you start an upgrade on your device, and then get a connection, your client talks to the server instead of the server talking to the client as before. This is bad. The reason why you cannot hack in clash of clans is because in order to hack you need to h@ck the servers. You can't use iFile because you will be out of sync with the server.
If Clash of Clans had an offline mode, hypothetically, you play on your device without a connection, anybody can change a number of files in clash of clans, get free stuff, and then connect with the server and the server will actually listen, which Therefore makes hacking (cheating) super easy which is why this shouldn't be allowed to happen; is why there isn't an offline mode.
Hope this helps.