NSManagedObject Subclasses - Core Data - page 29

Next to Class , replace Bowtie with Bow_Ties.Bowtie . This is the fully specified
class name for Bowtie.swift. This last step links the runtime Bowtie class to the
Bowtie entity in the data model editor.
Congratulations, you've just made your first managed object subclass in Swift!
Compared with key-value coding, this is a much better way of working with Core
Data entities. There are two main benefits:
1. Managed object subclasses unleash the syntactic power of Swift properties. By
accessing attributes using properties instead of key-value coding, you again
befriend Xcode and the compiler.
2. You gain the ability to override existing methods or to add your own convenience
methods. Note that there are some NSManagedObject methods you must never
override. Check Apple's documentation of NSManagedObject for a complete list.
To make sure everything is hooked up correctly between the data model and your
new managed object subclass, let's perform a small test.
Open AppDelegate.swift and replace didFinishLaunchingWithOptions with the
following implementation:
func application(application: UIApplication ,
didFinishLaunchingWithOptions
launchOptions: [ NSObject : AnyObject ]?) -> Bool {
/* Save test bow tie */
let entity = NSEntityDescription . entityForName ( "Bowtie" ,
inManagedObjectContext: managedObjectContext !)
let bowtie = Bowtie (entity: entity!,
insertIntoManagedObjectContext: managedObjectContext )
bowtie. name = "My bow tie"
bowtie. lastWorn = NSDate ()
managedObjectContext !. save ( nil )
/* Retrieve test bow tie */