Read and write data from a database

I have to develop an application for iPad, using Xcode, which has to store data in a database; the database must be accessible by all iPads which 开发者_运维知识库have the application installed. How can I go about this? Please provide me with the necessary details, and guides if possible. Thanks a lot in advance.

The easy way is create an XML database on a server and let the iDevice download it. Then in the iPhon application you have to write a XML parser.

I think that this is the easiest way