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vb.net print barcode labels Data: advanced techniques in Objective-C
Download from Wow! eBook <www.wowebook.com> QR Code Maker In Objective-C Using Barcode creation for iPhone Control to generate, create Quick Response Code image in iPhone applications. www.OnBarcode.comBarcode Generator In Objective-C Using Barcode creator for iPhone Control to generate, create Barcode image in iPhone applications. www.OnBarcode.comData: advanced techniques
DataMatrix Maker In Objective-C Using Barcode generator for iPhone Control to generate, create Data Matrix image in iPhone applications. www.OnBarcode.comBarcode Drawer In Objective-C Using Barcode drawer for iPhone Control to generate, create Barcode image in iPhone applications. www.OnBarcode.cominitWithKey:@"creationDate" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [sortDescriptors release]; [sortDescriptor release]; Make USS-128 In Objective-C Using Barcode generation for iPhone Control to generate, create EAN128 image in iPhone applications. www.OnBarcode.comEAN-13 Generation In Objective-C Using Barcode drawer for iPhone Control to generate, create UPC - 13 image in iPhone applications. www.OnBarcode.comExecutes request
Paint Code 3 Of 9 In Objective-C Using Barcode generation for iPhone Control to generate, create Code 3/9 image in iPhone applications. www.OnBarcode.comUCC - 12 Encoder In Objective-C Using Barcode printer for iPhone Control to generate, create UPC - E0 image in iPhone applications. www.OnBarcode.comNSError *error; NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; if (mutableFetchResults == nil) { NSLog(@"Error fetching result %@",[error description]); } [self setEntries:mutableFetchResults]; [mutableFetchResults release]; [request release]; Quick Response Code Drawer In None Using Barcode creator for Software Control to generate, create QR Code JIS X 0510 image in Software applications. www.OnBarcode.comQR Creation In Java Using Barcode creation for Android Control to generate, create QR Code 2d barcode image in Android applications. www.OnBarcode.comLocalizes array
Paint UPC-A In .NET Using Barcode generation for Visual Studio .NET Control to generate, create GTIN - 12 image in .NET framework applications. www.OnBarcode.comPrinting USS Code 128 In Visual Studio .NET Using Barcode creator for Visual Studio .NET Control to generate, create Code-128 image in Visual Studio .NET applications. www.OnBarcode.comThe first step in retrieving results from the database is to create the fetch request. After the request has been created, you must set its entity. The entity represents which object type you re retrieving. In this case, the entity is an Entry of your journal. After your request is created, you must tell it how to sort the results. If you omit this step, the ordering of the results will be undefined. This means the results returned could be in any order. The sort descriptor you create in B tells the request to sort the results by the creation date in ascending order. You can sort based on any field in your entity. The last thing you need to do is execute the request C. Notice that the request returns an NSMutableArray. This array contains all the objects retrieved from the database in the order specified by the sort descriptor. To keep these results around, you set them to a class variable D. When you have an array of objects on hand, you can begin modifying or deleting them. Let s look at modifying objects. Here s how you update a managed object: Encoding GS1 128 In None Using Barcode creator for Font Control to generate, create USS-128 image in Font applications. www.OnBarcode.comPrint UCC-128 In Objective-C Using Barcode creation for iPad Control to generate, create UCC.EAN - 128 image in iPad applications. www.OnBarcode.com- (void) update:(Entry *) entry { [entry setTitle:textField.text]; [entry setBody:textView.text]; [entry setCreationDate:[NSDate date]]; NSError *error; if (![self.managedObjectContext save:&error]) { NSLog(@"Error Saving: %@",[error description]); } } Print PDF-417 2d Barcode In .NET Using Barcode generation for ASP.NET Control to generate, create PDF417 image in ASP.NET applications. www.OnBarcode.comGenerate EAN13 In VS .NET Using Barcode generator for .NET framework Control to generate, create EAN 13 image in .NET applications. www.OnBarcode.comAs you can see, the code is almost identical to the code to add a new entry. The only difference is how the entry is retrieved. Instead of letting Core Data allocate a new entry for us, you modify one you already have on hand. Typically, this is first retrieved from the array you created in listing 9.13. As with updating, you must have a managed object on hand in order to delete it. You can t delete a managed object without first retrieving it. Here s how you delete a managed object from the database: Barcode Creation In VB.NET Using Barcode printer for .NET Control to generate, create Barcode image in Visual Studio .NET applications. www.OnBarcode.comBarcode Scanner In None Using Barcode recognizer for Software Control to read, scan read, scan image in Software applications. www.OnBarcode.comDownload from Wow! eBook <www.wowebook.com>
Barcode Encoder In None Using Barcode maker for Online Control to generate, create Barcode image in Online applications. www.OnBarcode.comPrinting European Article Number 13 In None Using Barcode generation for Online Control to generate, create GS1 - 13 image in Online applications. www.OnBarcode.comSummary -(void) delete:(Entry *) entry { [managedObjectContext deleteObject:entry]; [entries removeObject:entry]; NSError *error; if (![managedObjectContext save:&error]) { NSLog(@"Error deleted entry %@",[error description]); } } The delete method is fairly straightforward. The first thing to do is remove the object from the managed object context. Any time the context is saved after removing the object, it deletes that object from the data store. Next, you delete the object from the global array of entries so you can reflect the update to the user. If you don t do this, the user may still see the object in a table view, even though it s deleted forever when the application exits. Finally, you save the context. As with any changes made to the context, saving it makes them permanent. Summary As you ve seen, you have two powerful options to consider when storing large amounts of data on the iPhone and iPad. SQLite is great for anyone with prior experience with SQL and MySQL. You have the ability to use full SQL syntax to work with the records without having to learn a new design pattern. Core Data is Apple s response to solving the complexities associated with SQL. You no longer need to know complicated SQL syntax in order to have a fully functional database in your application. Core Data extracts much of the process and gives you high-level objects to work with as you please. In the next chapter, we ll move away from data storage and work with some of the cool hardware features of the iPhone and iPad. These include the accelerometer, GPS, and compass.
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