title: When does NSCache release the caches objects?
body: <p>I have implemented a list where a number of large images are being loaded asynchronously. I am using an instance of <code>NSCache</code> to store these <code>UIImage</code> files. As I scroll down, I load more and more images. I set this up and was profiling the app for allocations, and I noticed that the cache does not seem to be releasing any memory. The "Live Bytes" field has gone up to 165 MB and counting. What is the limit at which the cache starts freeing memory? Or do I have to set it myself?</p>