# RandomAccessCollection Implementations ## Topics ### Instance Properties [`var endIndex: AnyRandomAccessCollection.Index`](/documentation/Swift/AnyRandomAccessCollection/endIndex) The collection’s “past the end” position—that is, the position one greater than the last valid subscript argument. [`var startIndex: AnyRandomAccessCollection.Index`](/documentation/Swift/AnyRandomAccessCollection/startIndex) The position of the first element in a non-empty collection. ### Instance Methods [`func distance(from: AnyRandomAccessCollection.Index, to: AnyRandomAccessCollection.Index) -> Int`](/documentation/Swift/AnyRandomAccessCollection/distance(from:to:)) Returns the distance between two indices. [`func formIndex(after: inout AnyRandomAccessCollection.Index)`](/documentation/Swift/AnyRandomAccessCollection/formIndex(after:)) Replaces the given index with its successor. [`func formIndex(before: inout AnyRandomAccessCollection.Index)`](/documentation/Swift/AnyRandomAccessCollection/formIndex(before:)) Replaces the given index with its predecessor. [`func index(AnyRandomAccessCollection.Index, offsetBy: Int) -> AnyRandomAccessCollection.Index`](/documentation/Swift/AnyRandomAccessCollection/index(_:offsetBy:)) Returns an index that is the specified distance from the given index. [`func index(AnyRandomAccessCollection.Index, offsetBy: Int, limitedBy: AnyRandomAccessCollection.Index) -> AnyRandomAccessCollection.Index?`](/documentation/Swift/AnyRandomAccessCollection/index(_:offsetBy:limitedBy:)) Returns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index. [`func index(after: AnyRandomAccessCollection.Index) -> AnyRandomAccessCollection.Index`](/documentation/Swift/AnyRandomAccessCollection/index(after:)) Returns the position immediately after the given index. [`func index(before: AnyRandomAccessCollection.Index) -> AnyRandomAccessCollection.Index`](/documentation/Swift/AnyRandomAccessCollection/index(before:)) Returns the position immediately before the given index. ### Subscripts [`subscript(AnyRandomAccessCollection.Index) -> Element`](/documentation/Swift/AnyRandomAccessCollection/subscript(_:)-37hui) Accesses the element indicated by `position`. [`subscript(Range.Index>) -> AnyRandomAccessCollection.SubSequence`](/documentation/Swift/AnyRandomAccessCollection/subscript(_:)-6jydx) Accesses a contiguous subrange of the collection’s elements. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)