Core Data: Copying NSManagedObject Using Category

Question

I have two entities:

• Ticket
• TicketResolved

Both entities have the same attributes. What would be the the most efficient way to copy a Ticket NSManagedObject to TicketResolved NSManagedObject?

I'm thinking using a Category: Ticket+Copy be the least expensive way? If so, I would have to #import both Ticket and TicketResolved in the Category file.

Here is what I came up with, can someone please advise if this is the right way of going about it. I'm using NSManagedObjectSubclass for each entity.

Method in Ticket+Copy:

-(TicketResolved *)copyObjects:(Ticket *)ticket
{
     TicketResolved *ticketResolved = [NSEntityDescription insertNewObjectForEntityForName:@"TicketResolved" inManagedObjectContext:self.managedObjectContext];
     ticketResolved.attribute = ticket.attribute;
     // Assign rest of the ticketResolved attributes values this way
     return ticketResolved;
}

Now calling the Method

#import Ticket;
#import Ticket+Copy;

@implementation
....
Ticket *ticket = [NSEntityDescription insertNewObjectForEntityForName:@"Ticket" inManagedObjectContext:self.managedObjectContext];
TicketResolved *newTicketResolved = [ticket copyObjects:ticket];
// 'newTicketResolved' now has all the keys/values that 'ticket' had.

Is this a right approach or is there a simpler way to do this?

Answer 1

Thanks to @Tom, I did correct my error in the question.

Below is the solution that worked for me:

TicketResolved *ticketResolved = [NSEntityDescription insertNewObjectForEntityForName:@"TicketResolved" inManagedObjectContext:self.managedObjectContext];
NSArray *keys = [[[ticket entity] attributesByName] allKeys];
NSDictionary *dict= [ticket dictionaryWithValuesForKeys:keys];
[ticketResolved setValuesForKeysWithDictionary:dict];

The code above does not copy the Relationships Objects. For that I had to use the code below:

ticketResolved.relationshipObject = ticket.relationshipObject;

Answer 2

If Ticket and TicketResolved actually have the same attributes, the most efficient option is to:

• Get rid of TicketResolved
• Add a boolean flag on Ticket named resolved that you can set to YES when the ticket is resolved.
• Use this attribute it fetch requests to get either resolved or non-resolved tickets, whichever you need.

Then you don't actually need to copy any data, and not doing work is always more efficient than doing it.

If for some reason you really want two separate entities with the same attributes, basically you have it, you need to create a TicketResolved instance and have your code copy over every attribute value. The only major problem with your code is lines like this:

Ticket *ticket = [Ticket alloc]init];

You can't create managed objects like that, because you're not calling the designated initializer. You need to either use -[NSManagedObject initWithEntity:insertIntoManagedObjectContext:] or else use +[NSEntityDescription insertNewObjectForEntityForName:inManagedObjectContext:].