Using iTunes and the USB cable can provide MUCH faster file transfers thn WiFi.

To enable set IFileSharingEnabled key to true in Info.plist (note it is not a string)

The file share directory

When file sharing is enabled, the entire Documents folder is used for file sharing. Files that that are not intended for user access via the file sharing feature should be stored in another part of your application’s bundle (apps are rejected if files not intended for sharing are stored there).

Good Resources

Issues getting UIFileSharingEnabled to work