protocol Indexable Inheritance View Protocol Hierarchy → Associated Types Index : ForwardIndexType A type that represents a valid position in the collection. Valid indices consist of the position of every element and a "past the end" position that's not valid for use as a subscript. Import import Swift Instance Variables var endIndex: Self.Index Required The collection's "past the end" position. endIndex is not a valid argument to subscript, and is always reachable from startIndex by zero or more applications of successor(). Complexity: O(1) Declaration var endIndex: Self.Index { get } var startIndex: Self.Index Required The position of the first element in a non-empty collection. In an empty collection, startIndex == endIndex. Complexity: O(1) Declaration var startIndex: Self.Index { get } Subscripts subscript(_: Self.Index) Required Declaration subscript(position: Self.Index) -> Self._Element { get }