如何通过互联网更新数据库文件？

My App has a database file in its NSBundle. I want to get update database file from internet whenever new database file is available. and this should happen before app displays data from the database file. Here is the logic i am trying to use. i don't know if it makes sense or is there a better way to do it. an example will be awesomeMy App has a database file in its NSBundle. I w