When read large map tiles file at format, zMap may suspends on "Analysis Map Tiles" process or crash. The problem is caused by the database index for these files are not design for non-continuous zoom level and the conversion process is quite resouces-consuming on iOS device. To solve this problem, you will need pre-process for the map tiles file on the computer by Firefox with extension SQLite-manager (http://code.google.com/p/sqlite-manager/)
Start SQLite-Manager at Firefox by Tools>SQLite Manager.
