An abstract class whose subclasses enumerate collections of objects, such as arrays and dictionaries.
SDKs
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
Framework
- Foundation
Declaration
class NSEnumerator : NSObject
Overview
All creation methods are defined in the collection classes—such as NSArray, NSSet, and NSDictionary—which provide special NSEnumerator objects with which to enumerate their contents. For example, NSArray has two methods that return an NSEnumerator object: object and reverse. NSDictionary also has two methods that return an NSEnumerator object: key and object. These methods let you enumerate the contents of a dictionary by key or by value, respectively.
You send next repeatedly to a newly created NSEnumerator object to have it return the next object in the original collection. When the collection is exhausted, nil is returned. You cannot “reset” an enumerator after it has exhausted its collection. To enumerate a collection again, you need a new enumerator.
The enumerator subclasses used by NSArray, NSDictionary, and NSSet retain the collection during enumeration. When the enumeration is exhausted, the collection is released.