UIManagedDocument with Core Data by Alondo Brewington

Alondo discusses using UIManagedDocument with Core Data at CocoaHeads Raleigh in April 2012

Transcript

1. UIManagedDocument with CoreData Alondo Brewington abrewington@dtsquaredsoftware.com @abrewing
2. UIManagedDocument Subclass of UIDocument Core Data features
3. Benefits Asynchronous I/O Autosaving Unmodeled Data (Additional Content API) iCloud integration
4. Asynchronous I/O Snapshots taken for open/read /save work happens on a background queue Completion handler block executed on main queue
5. Data Load // Create UIManagedDocument with URL UIManagedDocument *myAppDatabase = [[UIManagedDocument alloc] initWithFileURL:myAppDBFileURL]; NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption, [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil]; myAppDatabase = options; [myAppDatabase saveToURL:myAppDBFileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success){ if (!success) { // Handle the error. }else { // Perform functions for created database (e.g. insert default data) } }];
6. Autosave Autosave by default Proceed with caution Particularly with relationships
7. Saving - (void)performUpdate { NSManagedObjectContext *context = myAppDatabase.managedObjectContext; NSSet *inserts = [context insertedObjects]; if ([inserts count]) { NSLog(@"Inserting %d new objects", [inserts count]); NSError * error = nil; if ([context obtainPermanentIDsForObjects:[inserts allObjects] error:&error] == NO) { NSLog(@"[DataManager performUpdate]! %@", error); } } [myAppDatabase updateChangeCount:UIDocumentChangeDone]; }
8. Saving [myAppDatabase saveToURL: myAppDatabase.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) { if (success) { NSLog(@"Success: saved database"); } }];
9. Migration // If legacy store exists, copy it to the new location NSURL *legacyPersistentStoreURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"OldDatabase.sqlite"]; NSFileManager* fileManager = [NSFileManager defaultManager]; if ([fileManager fileExistsAtPath:legacyPersistentStoreURL.path]) { NSLog(@"Old db exists"); NSError* thisError = nil; [fileManager replaceItemAtURL:storeURL withItemAtURL:legacyPersistentStoreURL backupItemName:nil options:NSFileManagerItemReplacementUsingNewMetadataOnly resultingItemURL:nil error:&thisError]; NSLog([thisError localizedDescription]); } return [super configurePersistentStoreCoordinatorForURL:storeURL ofType:fileType
10. Demo ToDo List App Data Model DataManage class File Package
11. Resources WWDC 2011: Session 303 - What’s New in Core Data on iOS WWDC 2011: Storing Documents in iCloud using iOS 5 iTunes: Stanford - iPad and iPhone Application Development
12. Questions