Class

NSEnumerator

An abstract class whose subclasses enumerate collections of objects, such as arrays and dictionaries.

Declaration

@interface NSEnumerator<__covariant ObjectType> : 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: objectEnumerator and reverseObjectEnumerator. NSDictionary also has two methods that return an NSEnumerator object: keyEnumerator and objectEnumerator. These methods let you enumerate the contents of a dictionary by key or by value, respectively.

You send nextObject 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.

Topics

Getting the Enumerated Objects

allObjects

The array of unenumerated objects.

- nextObject

Returns the next object from the collection being enumerated.

Relationships

Inherits From

See Also

Iteration

NSFastEnumeration

A protocol that objects adopt to support fast enumeration.

NSEnumerationOptions

Options for block enumeration operations.

NSSortOptions

Options for block sorting operations.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software