Why is NSURLSession don't use my configured NSURLCache?

Seems like there are two potential issues: Your cache is too small. Historically, it wouldn't cache if the item being cached exceeded 10% of the total cache size. You're checking the disk usage 0.5 seconds after the last request. That might be too soon for the cache to be written to persistent storage. Below I use a bigger cache and wait 10 seconds before final check of disk usage, and the cache w