When (not) to abuse NSUserDefaults

Question

I wonder what the guidelines are for:
1 - how often I can read from NSUserDefaults
2 - how much data I can reasonably store in NSUserDefaults

Obviously, ther

Answer 1

The main performance issue no-one here is mentioning is that the user’s home directory may be on a network volume, and may not be particularly fast. It’s not an ideal situation, but it happens, so if you’re worried about performance that’s what you should be testing against.

That said, NSUserDefaults uses an in-memory cache, and the cost is only incurred when synchronizing. According to the documentation, synchronization happens “automatically … at periodic intervals”; I believe this only applies if something has changed, though.

So, for the case of checking whether the computer is a player, using NSUserDefaults once a frame shouldn’t be a problem since it’s cached. For storing game state, it may be a performance problem if you updated it constantly, and as Peter Hosey says it’s a semantic abuse.