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Running the project in Software Encode ANSI/AIM Code 39 in Software Running the project

Running the project use software code-39 implementation toembed barcode 39 with software Planet [ 122 ]. 5 . After entering a Code 39 Extended for None few names, our table view may appear, as shown in the following image (a). We can delete any name by selecting the corresponding Edit icon of the table cell. A Delete button appears on selecting the Edit icon of a table cell, as shown in the following image (b).

The name will be deleted from the table view on selecting the Delete button and the table view is refreshed to show the modification applied, as shown in the following image (c):. In the preceding application, we have made use of a single managed object context. In the next chapter, we will modify the preceding application to have multiple managed object context. In the preceding module, we used a single instance of the Managed Object Context by the name managedObjectContext and all the modifications (insert, delete, and so on) were implemented on the same instance.

In the next chapter, we will see what changes we have to do in the module if we plan to maintain more than one instance of Managed Object Context.. [ 123 ]. Creating, Listing, and Deleting Names of Customers Summary. In this chapter, we first saw the meaning of the code that is automatically generated for us by Core Data in the Application Delegate files. Then, we saw the step-bystep procedure of saving, listing, and deleting customer names. We have also learnt about the concept of KVC and its methods used in setting and retrieving attribute values from the managed object.

We also saw the different methods of the NSFetchedResultsControllerDelegate protocol. In the next chapter, we will see how to implement the concept of multiple managed object contexts to our application and also how to merge the information in different managed object contexts. We will also learn how to apply the knowledge gained in this chapter to maintain a customer"s information, that is, we will see step-by-step how to save, display, and delete the customer"s information.

. [ 124 ]. Creating, Listing, Displaying, and Deleting Records of Customers In the previous barcode 39 for None chapter, we understood the meaning of the code that is automatically generated for us by Core Data in the Application Delegate files. We also developed the application that saves, lists, and deletes customer names. In this chapter, we will enhance the same application to save, list, display, and delete the information of a customer.

But before we do so, we will learn to implement the concept of multiple managed object contexts to our application and also how to merge the information in different managed object contexts. We will also learn to apply the knowledge gained so far such as the concept of KVC, its methods used in setting and retrieving attribute values from the managed object, different methods of the NSFetchedResultsControllerDelegate protocol, and so on, to our application..

Understanding multiple managed object context In multiple mana Code 3 of 9 for None ged object context concept, we make several instances of managed object context and each instance works independently without having knowledge of what modifications are implemented in other instances. In order to keep all instances informed of different modifications performed in each context, a notification is broadcasted by a managed object context when any save or delete operation is performed on it. Like, if a managed object context completes a save operation, it broadcasts an NSNotification with the NSManagedObjectContextDidSaveNotification key.

. Creating, Listing, Displaying, and Deleting Records of Customers The benefit of t Software 39 barcode his notification is that any managed object context that listens to the notification NSManagedObjectContextDidSaveNotification can update its contents by invoking the method mergeChangesFromContextDidSaveNotification:. This method updates the contents of managed object context (with the managed object context that broadcasted the notification) and will also notify any observers of those changes..

The notification that is broadcasted when a delete operation is performed on a managed object is: NSManagedObjectContextObjectsDidChangeNotification notification.. So, broadcasting bar code 39 for None notification is a technique to synchronize different managed objects. Every view maintains an observer to a specific key. When a notification with that key is broadcasted, the view invokes a method to handle the notification.

. NSNotification i s an object that is broadcasted by an NSNotificationCenter object to other objects. The NSNotification object, also known as notification, is received by the observers of that notification. The notification consists of a name and an object where name is a tag that identifies the notification and the object is the object that posted the notification.

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