CODEWITHSUNDEEP
objective-ccore-data
doc92606
doc92606

Reputation: 701

Core Data Reading Data

I am a VERY new beginner to Core Data and I have recently been trying to read and write data. I created an entity named "Person" with the entities "name" and "age". I also have a textfield name "personName" and a textfield named "personAge".

- (IBAction)readData:(id)sender
{
    NSNumber *ageNum = [NSNumber numberWithInteger:personAge.text.integerValue];
    Person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:managedObjectContext];

    newPerson.name = personName.text;
    newPerson.age = ageNum;

    NSLog(@"Person %@ name is %@", personName.text, ageNum);
}

When I load the app, all i get is SIGABRT. Even when all I put in the method is

 Person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"Person"     inManagedObjectContext:managedObjectContext];

All help is appreciated.

Upvotes: 0

Views: 724

Answers (2)

Kundan
Kundan

Reputation: 3082

For Adding values to the core data you can do so:-

- (IBAction)save:(id)sender {
    NSManagedObjectContext *context = [self managedObjectContext];

    // Create a new managed object
    NSManagedObject *person = [NSEntityDescription insertNewObjectForEntityForName:@"Person" inManagedObjectContext:context];
    [person setValue:self.personName.text forKey:@"name"];
    [person setValue:self.personAge.text forKey:@"age"];

    NSError *error = nil;
    // Save the object to persistent store
    if (![context save:&error]) {
        NSLog(@"Can't Save! %@ %@", error, [error localizedDescription]);
    }    
}

For fetching the values from core data:-

NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Person"];
    self.personValues = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

here personValues is a NSMutableArray. For better understanding about these please go through this link.

http://www.appcoda.com/introduction-to-core-data/

Hope this will help you out.

Upvotes: 1

smyrgl
smyrgl

Reputation: 854

If you are very new to Core Data, try using the MagicalRecord library which provides a series of helper categories for dealing with a lot of the boiler plate setup of Core Data.

Which brings me to the question you are asking: are you sure your Core Data stack is being setup correctly? Check to make sure your Managed Object Context is valid along with a proper Persistent Store Coordinator.

Best thing to do: put a breakpoint during the Core Data stack setup and step through it making sure everything is setup properly. Or install MagicalRecord and do one method call to [MagicalRecord setupAutomigratingCoreDataStack]...

Upvotes: 0

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