# RandomAccessCollection Implementations ## Topics ### Instance Properties [`var endIndex: CollectionOfOne.Index`](/documentation/Swift/CollectionOfOne/endIndex) The “past the end” position—that is, the position one greater than the last valid subscript argument. [`var indices: Range`](/documentation/Swift/CollectionOfOne/indices-swift.property) The indices that are valid for subscripting the collection, in ascending order. [`var startIndex: CollectionOfOne.Index`](/documentation/Swift/CollectionOfOne/startIndex) The position of the first element. ### Instance Methods [`func distance(from: Self.Index, to: Self.Index) -> Self.Index.Stride`](/documentation/Swift/CollectionOfOne/distance(from:to:)) Returns the distance between two indices. [`func index(Self.Index, offsetBy: Self.Index.Stride) -> Self.Index`](/documentation/Swift/CollectionOfOne/index(_:offsetBy:)) Returns an index that is the specified distance from the given index. [`func index(Self.Index, offsetBy: Int, limitedBy: Self.Index) -> Self.Index?`](/documentation/Swift/CollectionOfOne/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: CollectionOfOne.Index) -> CollectionOfOne.Index`](/documentation/Swift/CollectionOfOne/index(after:)) Returns the position immediately after the given index. [`func index(before: CollectionOfOne.Index) -> CollectionOfOne.Index`](/documentation/Swift/CollectionOfOne/index(before:)) Returns the position immediately before the given index. ### Subscripts [`subscript(Range) -> CollectionOfOne.SubSequence`](/documentation/Swift/CollectionOfOne/subscript(_:)-16mfr) Accesses a contiguous subrange of the collection’s elements. [`subscript(Int) -> Element`](/documentation/Swift/CollectionOfOne/subscript(_:)-876qi) Accesses the element at the specified position. --- 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)