Sams Teach Yourself Core Data for Mac® and iOS in 24 Hours, Second Edition

Hour 18. Validating Data

What You’ll Learn in This Hour:

• Creating validation rules in the data model

• Moving data between interface fields and data model objects

• Using formatters

• Creating subclasses of NSManaged object

Using Validation Rules in the Data Model

There are two aspects to data validation:

• Specifying the validation rules

• Implementing them

In this hour, you learn how to set some validation rules for a data model and how they take effect as people enter data. After that, you learn how to modify the default behavior so that you provide your own validation error messages.

The focus in this hour is on the rules. Once you have them in place, some will be managed automatically for you—particularly on Mac OS with its bindings ...