The Core Data Stack - Core Data - page 52

didFinishLaunchingWithOptions
launchOptions: [ NSObject : AnyObject ]?) -> Bool {
let navigationController =
self . window !. rootViewController as UINavigationController
let viewController =
navigationController. topViewController as ViewController
viewController. managedContext = coreDataStack . context
return true
}
This code propagates the managed context from your CoreDataStack object
(initializing the whole stack in the process) to ViewController .
Finally, add the following two UIApplicationDelegate methods to the AppDelegate
class:
func applicationDidEnterBackground(application: UIApplication ) {
coreDataStack . saveContext ()
}
func applicationWillTerminate(application: UIApplication ) {
coreDataStack . saveContext ()
}
These methods ensure that Core Data saves any pending changes before the app is
either sent to the background or terminated for whatever reason.
Modeling your data
Now that your shiny new Core Data stack is securely fastened to your application
delegate, it's time to create your data model.
Head over to your Project Navigator and… Wait a second. There's no data model
file! That's right. Since I generated this sample application without enabling the
option to use Core Data, there's no .xcdatamodel file.
No worries. Go to File\New\File… , select the iOS\Core Data\Data Model
template and click Next . Name the file Dog Walk.xcdatamodeld and click Create
to save the file: