Question

In Apple’s Performance Tuning Guide there is a writing:

Avoid writing cache files to disk. The only exception to this rule is
when your app quits and you need to write state information that can
be used to put your app back into the same state when it is next
launched.

I’m saving a lot of cache files in Library/Cache directory, because my app deals with web services, and nobody likes the white screen. What does this statement mean? I shouldn’t do this or what?

Thank you!

Answer 1

Well, “avoid” means “avoid if possible, because writing/reading is relatively slow”. If by caching a small amount of data (I assume the definitions of the web services retrieved from somewhere?) you can improve the performance of your app’s startup, by all means do it. If you are only using this data for one run of your application, and the next run will re-fetch this anyway, use an in-memory cache.

Library\Caches is basically designed to store data you fetched from somewhere which provides performance boosts when stored locally.

The text from Apple feels like more a general guideline against overusing storage if you don’t need data to persist from one run of your application to another.