Q:

Core Data. Detect same object?

I have 2 Core Data objects of the same type. I got them via different ways.
At the same time these objects have an NSString field (identifier).
So what is better?
1)compare objects via isEqual:
2)compare objects via == (is it possible in general?)
3)compare objects' fields via isEqualToString:?

A:

Basically, never use == on objects. Always use isEqual:.
If you're using a predicate then you can use LIKE on the identifier.

