Basic Data Persistence
So far, we’ve focused on the controller and view aspects of the MVC paradigm. Although several of our applications have read data out of the application bundle, none of them has saved data to any form of persistent storage—nonvolatile storage that survives a restart of the computer or device. So far, with the exception of Application Settings (in Chapter 12), every sample application either did not store data or used volatile (i.e., nonpersistent) storage. Every time one of the sample applications launched, it appeared with exactly the same data it had the first time you launched it.
This approach has worked for us up to this point. But in the real world, your applications will need to persist data. When users ...