I have a dictionary of objects; they are all POCO objects that should be serializable. What technique should I look at for writing these to disk. I'm looking for the simplest option to write a few lists to save state.
I think I have 3 options.
plist files. However this seems to be limited to only storing predefined objects (strings, numbers etc) not objects (like a person with a name and age).
CoreData. (New in 3.0) This would work well; however my data model would need to change to make this work. This would be a massive rework and I'm not sure if it is worth the effort.
SQLLite. Implement a simple SQL database to read to and from. I have done the least amount of reserch into this one, but I don't want to have to 'rewrite' some of the core data ORM functions.
You do this in the same way you'd do it on Mac OS X: your POCOs must conform to the NSCoding protocol. See here for a conceptual reference, and here for the NSCoding reference.
If the data isn't that crazy extensive and you don't have ridiculously complicated relationships between your objects, writing everything out as a plist is probably your best option; it's very fast to execute and simple to implement in your code. Like you said, CoreData will probably be a lot of extra work to adapt your code to, and sqlite really is only good for storing data that's perfect to be stored in a relational database. Keep in mind that sqlite is also slower and uses more resources than working with binary plists.