coredata how to change default NSSet to NSMutableArray

问题

CoreData one-to-many default to generate NSSet ,how to change NSSet to NSMutableArray?I try to change it manually,but get error:

 _NSFaultingMutableSet filteredArrayUsingPredicate:]: unrecognized selector sent to instance 0x1ed35e40'

回答1:

NSSet has the method allObjects, which returns an NSArray.

To get an NSMutableArray you could do this:

NSMutableArray *array = [NSMutableArray arrayWithArray:myCoreDataObject.mySet.allObjects];

Note: order is not guaranteed to be the same every time (sets aren't ordered). If order is important to you, consider an NSOrderedSet instead.

See also the docs on NSSet:

https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSSet_Class/Reference/Reference.html

PS:

The reason you're getting said error:

NSSet (or _NSFaultingMutableSet for that matter) doesn't have a method called filteredArrayUsingPredicate.

来源：https://stackoverflow.com/questions/14617194/coredata-how-to-change-default-nsset-to-nsmutablearray