Do NSManagedObjects come with any kind of unique identifier?
I need to fetch a couple of objects but there is a large chance they have identical attributes, so how can I, after fetching these objects, differentiate them?
Thanks.
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Do NSManagedObjects come with any kind of unique identifier?
I need to fetch a couple of objects but there is a large chance they have identical attributes, so how can I, after fetching these objects, differentiate them?
Thanks.
Yes. Every NSManagedObject has an
-objectIdaccessor which returns anNSManagedObjectIDinstance. These uniquely identify the object in question. You can then retrieve the object again using either of NSManagedObjectContext’s methods-objectWithID:or-existingObjectWithID:error:.Note that if the object has not yet been saved after insertion, the object ID will be a temporary ID that will change when it’s saved. You can force a persistent ID to be assigned with
-[NSManagedObjectContext obtainPermanentIDsForObjects:error:], although this is just as expensive as an actual save.