I've developed a reading tracking app in Swift and for simplicity's sake I used arrays for my model. It stores some data about the books a user reads and a small image of the cover. I save them to disk periodically for persistence. Now I'm wondering as people use the app, at what point would it be wise to convert my model to using CoreData instead? And would you make that decision based on file size, or number of entries? I ran a test by increasing the number of entries and it seemed like everything worked fine until I started getting into hundreds of entries, at which point the UI started getting laggy. It would probably take a user a pretty long time (years?) to reach that point, but I'd rather know sooner not later if I'm going to have to make a switch.
I've tried searching around for some guidelines and haven't found anything helpful. Anybody with experience out there have any suggestions?