NSURLCache does not clear stored responses in iOS8

NSURLCache is broken on iOS 8.0.x - it never purges the cache at all, so it grows without limit. See http://blog.airsource.co.uk/2014/10/11/nsurlcache-ios8-broken/ for a detailed investigation. Cache purging is fixed in the 8.1 betas - but removeCachedResponseForRequest: is not.

removeCachedResponsesSinceDate: does appear to work on iOS 8.0 - an API that was added for 8.0, but hasn't made it to the docs yet (it is in the API diffs). I am unclear what use it is to anyone - surely what you normally want to do is remove cached responses before a particular date.

removeAllCachedResponses works as well - but that's a real sledgehammer solution.