Question

NSManagedObject *parent = [NSEntityDescription insertNewObjectForEntityForName:@"Parent" inManagedObjectContext:self.managedObjectContext];
NSManagedObject *child = [NSEntityDescription insertNewObjectForEntityForName:@"Child" inManagedObjectContext:self.managedObjectContext];
[child setValue:parent forKey:@"parent"];

That doesn’t seem to work for me, but I can do something like this:

[child setValue:"John" forKey:@"name"];

Thanks for the help!

Answer 1

If the relationship has been defined in the ManagedObjectModel you can use

[parent setValue:child forKey:@"childObject"];

This code example assumes that your Entity Parent has a relationship attribute set called childObject.

To use the . accessor for a property of a NSManagedObject you will need to subclass it.
Select your Entity and click Create NSManagedObject Subclass from the Editor Menu

Then instead of Creating your objects as NSManagedObjects, create them as Parent and Child classes

#import "Parent.h"
#import "Child" 
Parent *parent = [NSEntityDescription insertNewObjectForEntityForName:@"Parent" inManagedObjectContext:self.managedObjectContext];
Child *child = [NSEntityDescription insertNewObjectForEntityForName:@"Child" inManagedObjectContext:self.managedObjectContext];
parent.childObj = child;