ISO8601DateFormatter/ISO8601DateFormatter — pull request #1 by GrahamDennis (2013-01-28 00:54:09+00:00)
Title: Make ISO8601DateFormatter thread-safe.

Concurrent `NSMutableDictionary` access isn't thread-safe. I've replaced the `NSMutableDictionary *timeZonesByOffset` with an `NSDictionary` which is thread-safe for concurrent read access. Modifying the dictionary is protected by a serial dispatch queue.