"After apple operating system upgrading to 3.0 , offline maps have of
lots problems. These issues are mainly originated from the fact that
apple has changed the behavior of cache access . First of all, cache
data can not a Symbolic-link, it must be a real file (so, future
version might disable the function 'Link'). Secondly, in the state of
the network connection, iPhone will write into the cache; If it found
that it is unable to write, Maps will automatically delete the
readable file and re-establish a cache file. In other words, we
recommend that you use OfflineMaps when there is no network connection