Best database for iOS and Mac?

On the iPhone the choice is between SQLite and Core Data - Core Data is in many ways a wrapper for SQLite doing a lot of the heavy lifting for you. Core Data is available on the Mac as well. CD is really nice, I recommend using it!

 

This is absolutely true, and I highly recomend Core Data as well. I'll expand a bit by saying that in my experince the difference between Core Data and SQLite is that Core Data is very object oriented. But as far as iOS integration, Core Data is a lot cleaner and easier to implement.

Example 1: Let's say you want to select a number of records and delete them, with SQLite you can do this in one fell swoop. In Core Data you'll have to loop over the objects individually which will make things slower.

Example 2: Let's say you want to display a series of records in a table view. In SQLite you'll have a lot of boilerplate code to write to do this. In iOS you can simply use the NSFetchedResultsController and you get a lot of nice features and a working table view on the order of a few hours or less.

So if your database will be really large, you may want to use SQLite, but I would think twice before choosing that route, as it is certainly the path of greatest resistance.