hmm
Hi there,
I use a relational database in my desktop applications because they provide a quick and efficient means of organizing, entering, editing, deleting, and searching data (especially large amounts). The SQL query language is a powerful being.
If I am making a simple app for the desktop with only a few lines of data, I will use a flat file because the benefits of SQL do not outweigh the overhead of SQL.
I see no reason to look at it any differently on the iPhone (or any phone for that matter).
If the phone in question contains support for SQL and can run it reasonably quickly and efficiently (which the iPhone can), then SQL can (and should, in my opinion) be used if the amount of data in question is large enough to warrant the overhead involved.
As far as the methods not being in objective C, that is something you will run into a lot. I was writing a linux console based server in C++ a few years ago and I was using the MySQL library. I did not like it in C (I was using C++) so I found a C++ wrapper.
It is quite possible you will find an sqlite wrapper in objective C already or soon.