Question

Below is my code snippet:

NSFetchRequest *request= [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Login" inManagedObjectContext:self.managedObjectContext];
NSPredicate *predicate =[NSPredicate predicateWithFormat:@"userid==%@ AND password==%@",useridentered, passwordentered];
[request setEntity:entity];
[request setPredicate:predicate];
NSError *anyError=Nil;
NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:request error:&anyError];

Login *login = [fetchedObjects objectAtIndex:0];
Information *information = [NSEntityDescription insertNewObjectForEntityForName:@"Information" inManagedObjectContext:self.managedObjectContext];
login.information = information;
login.information.title = informationTitleTextView.text;
login.information.info_1 = information1textview.text;
login.information.info_2 = information2textview.text;

[self.managedObjectContext save:nil];  // write to database
NSLog(@"login.information %@",login.information.title);
NSLog(@"login.title %@", login.userid);
   [self.delegate savebuttontapped:self];

The problem is, it works fine for the first time. But when i again add information for the same user it overwrites the existing one. How to make sure that it gets written to next line?

Answer 1

You are creating a new managed object for the information (new DB row):

Information *information = [NSEntityDescription insertNewObjectForEntityForName:... inManagedObjectContext:...];

And then you assign it to the user.

login.information = information;

This does not remove the old information from the DB, but the user loses relationship with it.

I suppose that what you want is having more than one Information instances connected to one Login instance.
That means you have to open your Managed Object Model and change the one-to-one relationship into one-to-many relationship.

Then your code will be:

[login.informations addObject:information];

or

information.login = login;