iPhone - Create non-persistent entities in core data

Question

Hi everyone,

I would like to use entity objects but not store them... I read that I could create them like this:

myElement = (Element *)[NSEntityDescription insertNewObjectForEntityForName:@"Element" inManagedObjectContext:managedObjectContext];

And right after that remove them:

[managedObjectContext deleteObject:myElement];

then I can use my elements:

myElement.property1 = @"Hello";

This works pretty well even though I think this is probably not the most optimal way to do it...

Then I try to use it in my UITableView... the problem is that the object get released after the initialization. My table becomes empty when I move it!

Thanks

edit: I've also tried to copy the element ([myElement copy]) but I get an error...

Answer 1

couldn't you just do

Element *myElement = [[Element alloc] init];

Then do with it whatever you want, presumably you will add it to an array so it says around for your UITableView.

Answer 2

If you create a managed object without saving into the persistent store then you are misunderstanding managed object. You would better create an Array with values to populate to the table view instead of create the managed object.

A small question? Why you delete it immediately after the creation? How can that object be populated into the table view if you are trying to delete it immediately after you created it?

Answer 3

Hi,

Maybe you can try to have two store coordinators in your project. One which have persistence, and the other with no persistence.

Regards, Quentin

Answer 4

Consider using transient objects --- that are handled by the managed object context like any other object, but not written to disk on a save operation. They are typically employed to model runtime-only objects, as I suspect you are trying to do.

Here is some info on them: http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/CoreData/Articles/cdNSAttributes.html

http://2pi.dk/tech/cocoa/transient_properties.html