How to update data available in coredata? - ios

Question

Here I got the value in fetchedObjects. How can I update the value in the array?
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Reserve" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
//NSSortDescriptor tells defines how to sort the fetched results
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"number" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
NSLog(#"sort count%d",[sortDescriptors count]);
fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:#"Root"];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"(number = 100)", self.txtReserve.text];
// [fetchRequest setPredicate:predicate];
[fetchedResultsController.fetchRequest setPredicate:predicate];
self.fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
NSLog(#"Count of array::::%d",[fetchedObjects count]);
NSManagedObject *device = [fetchedObjects objectAtIndex:0];
NSLog(#"device::::%#",device);

Answer 1

I suggest that you read/watch some of the many books/tutorials on Core Data. You are missing a very basic understanding of the technology.
First, the objects you receive represent objects in the database, you have to know the entity descriptions to get the data. For example, the most basic way to get the "number" attribute of the "Reserve" entity would be...
[managedObject valueForKey:#"number"];
If you use Xcode (or a tool called mogenerator) you can have subclasses generated for your entities, and can more easily access the data via custom accessor methods.