Use arrays, dictionaries, sets, and specialized collections to store and iterate groups of objects or values.
Framework
- Foundation
Collections
Topics
Basic Collections
struct ArrayAn ordered, random-access collection.
struct DictionaryA collection whose elements are key-value pairs.
struct SetAn unordered collection of unique elements.
Indexes
struct IndexA list of indexes that together represent the path to a specific location in a tree of nested arrays.
struct IndexA collection of unique integer values that represent the indexes of elements in another collection.
Specialized Sets
class NSCountedA mutable, unordered collection of distinct objects that may appear more than once in the collection.
class NSOrderedA static, ordered collection of unique objects.
class NSMutableA dynamic, ordered collection of unique objects.
Purgeable Collections
class NSCacheA mutable collection you use to temporarily store transient key-value pairs that are subject to eviction when resources are low.
class NSPurgeableA mutable data object containing bytes that can be discarded when they're no longer needed.
Pointer Collections
class NSPointerA collection similar to an array, but with a broader range of available memory semantics.
class NSMapA collection similar to a dictionary, but with a broader range of available memory semantics.
class NSHashA collection similar to a set, but with broader range of available memory semantics.
Iteration
class NSEnumeratorAn abstract class whose subclasses enumerate collections of objects, such as arrays and dictionaries.
protocol NSFastA protocol that objects adopt to support fast enumeration.
struct NSIndexAn iterator suitable for enumerating the elements of an index set.
struct NSEnumerationOptions for block enumeration operations.
struct NSSortOptions for block sorting operations.
Special Semantic Values
class NSNullA singleton object used to represent null values in collection objects that don’t allow nil values.
let NSNotA value indicating that a requested item couldn’t be found or doesn’t exist.
See Also
Fundamentals
Numbers, Data, and Basic Values
Work with primitive values and other fundamental types used throughout Cocoa.
Strings and Text
Create and process strings of Unicode characters, use regular expressions to find patterns, and perform natural language analysis of text.
Dates and Times
Compare dates and times, and perform calendar and time zone calculations.
Units and Measurement
Label numeric quantities with physical dimensions to allow locale-aware formatting and conversion between related units.
Data Formatting
Convert numbers, dates, measurements, and other values to and from locale-aware string representations.
Filters and Sorting
Use predicates, expressions, and sort descriptors to examine elements in collections and other services.