Question

A<<–>B

I had a one-to-many relationship in my app that was adding things to coredata, just fine.

But I switch to:

A<<–>>B

Still using the following code,

[A setValue:myValue forKey:@"aRelationshipToB"];

throws the error.

‘NSInvalidArgumentException’, reason: ‘Unacceptable type of value for to-many relationship: property = “RowersBoat”; desired type = NSSet;

I’m sure that I’m just missing something or just lack the knowledge about coredata, could anyone give me some direction here, or maybe write out just a bit of code. That would really help.

Thanks

Answer 1

It’s because many-to-many relationship requires set of objects (NSSet). Use this code instead:

NSSet *mySet = [NSSet setWithObjects:myValue,nil];
[A setValue:mySet forKey:@"aRelationshipToB"];