Data security

Hi there,

I was curious about one thing : if I want all the data from my app to be secure (meaning that I want nobody to be able to steal it easily), should I do something specific ?
I see three cases :

[ol]Using no core-data, no database: is the data stored in the app secure ? Or can anybody take it easily and do whatever he wants with it ?[/ol]
[ol]Using CoreData, we get a SQLite database within the app. Is it more secure than using no core-data ?[/ol]
[ol]Using an external database on a server (a SQL database for example): do we need to get there to have a secure database ?[/ol]

I am talking about a subject I don’t know so much about…
I know that any good hacker can do anything he (or she) wants with an app and its data, so my question is more regarding the rest of the world : how can I make the data of my app safe from any easy stealing ? What is the lightest but safe enough structure I would need ?

I hope I made myself clear… Thanks for your answers !