“Critically, almost all of the data is static, and can be freely discarded. iOS does not have a swapfile, so if you use too much dynamic memory, the OS gives you a warning or two, then kills your process. … If you read all your game data into memory, the OS can’t do anything with it, and you are in danger. However, if all of your data is in a read-only memory mapped file, the OS can throw it out at will. This will cause a game hitch when you need it next, but it beats an abrupt termination.”
John Carmack discusses RAGE on iOS
I’ve been telling people this for a couple of years now— hopefully now they’ll actually start taking notice ;o)