#LRUCache

Your mobile-device’s RAM is limited; and when you hit the limit, you’ll get a memory warning. Failing to release memory when you receive this warning will crash your app.

Purpose:      LRUCache enhances data-access by storing frequently-used data in memory (cache) and allowing the cache to purge least-recently-used (LRU) data.

‘MyLRU’ is a proof-of-concept of using LRU (Least Recently Used) cache design pattern. ‘MyLRU’ serializes user-data (NSData) into a NSData object within the in-memory cache layer and archive and unarchive some of the cache’s contents when memory is limiting.

Modus Operandi:      A dictionary is used to hold your cached data in memory. There’s a size limit to the memory; so when anything is added to the cache after it’s full, the least-recently used object (least recently used) should be saved to file (flash memory).

     This code also handles memory warnings and write the in-memory cache to flash memory (as files). All in-memory cache are written to flash memory (files) when the app is closed or quit or when it enters the background.

Variables:

• A NSMutableDictionary for storing the cache data.
• A NSMutableArray is used to keep track of recently-used items, in chronological order, and an integer that limits the maximum size of this cache.

The @synchronized directives wrap thread-sensitive portions of the code to allow for thread safety.

A Unit-Testing target is provided.