调用“ allObjects”时，对象的NSSet中的NSArray崩溃

Question

I have an core data NSSet of objects through a relationship that I am trying to put into an array.

When I call the 'allObjects' selector I get a crash on my object in the NSSet that the selector does not exist. Well, it obviously doesn't, but how do I get my data to copy into the array?

Heres the code that crashes.

NSArray *items = [surveyCategory.surveyQuestions allObjects];

Inside my surveyQuestions NSSet are SurveyQuestion objects. And this throws the error `[SurveyQuestion allObjects]: unrecognized selector sent to instance

Any ideas on how to fix this?

thanks

Answer 1

From the error message it looks as if surveyQuestions is not a to-many relationship as you expect, but a to-one relationship, so that surveyCategory.surveyQuestions is a SurveyQuestion object and not a set.

Perhaps you changed the Core Data model and did not re-create the managed object subclass file, so that the compiler did not complain.