---
title: Collections
framework: foundation
role: collectionGroup
role_heading: API Collection
path: foundation/collections
---

# Collections

Use arrays, dictionaries, sets, and specialized collections to store and iterate groups of objects or values.

## Topics

### Basic Collections

- [Array](swift/array.md)
- [Dictionary](swift/dictionary.md)
- [Set](swift/set.md)

### Indexes

- [IndexPath](foundation/indexpath.md)
- [IndexSet](foundation/indexset.md)

### Specialized Sets

- [NSCountedSet](foundation/nscountedset.md)
- [NSOrderedSet](foundation/nsorderedset.md)
- [NSMutableOrderedSet](foundation/nsmutableorderedset.md)

### Purgeable Collections

- [NSCache](foundation/nscache.md)
- [NSPurgeableData](foundation/nspurgeabledata.md)

### Pointer Collections

- [NSPointerArray](foundation/nspointerarray.md)
- [NSMapTable](foundation/nsmaptable.md)
- [NSHashTable](foundation/nshashtable.md)

### Iteration

- [NSEnumerator](foundation/nsenumerator.md)
- [NSFastEnumeration](foundation/nsfastenumeration.md)
- [NSFastEnumerationIterator](foundation/nsfastenumerationiterator.md)
- [NSIndexSetIterator](foundation/nsindexsetiterator.md)
- [NSEnumerationOptions](foundation/nsenumerationoptions.md)
- [NSSortOptions](foundation/nssortoptions.md)

### Special Semantic Values

- [NSNull](foundation/nsnull.md)
- [NSNotFound](foundation/nsnotfound-9t5v2.md)
- [NSNotFound](foundation/nsnotfound-4qp9h.md)

## See Also

### Fundamentals

- [Numbers, Data, and Basic Values](foundation/numbers-data-and-basic-values.md)
- [Strings and Text](foundation/strings-and-text.md)
- [Dates and Times](foundation/dates-and-times.md)
- [Units and Measurement](foundation/units-and-measurement.md)
- [Data Formatting](foundation/data-formatting.md)
- [Filters and Sorting](foundation/filters-and-sorting.md)