protocol _CollectionType This protocol is an implementation detail of CollectionType; do not use it directly. Its requirements are inherited by CollectionType and thus must be satisfied by types conforming to that protocol. Inheritance _SequenceType 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. _Element Import import Swift Instance Variables var endIndex: 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(). Declaration var endIndex: Index { get } var startIndex: Index Required The position of the first element in a non-empty collection. Identical to endIndex in an empty collection. Declaration var startIndex: Index { get } Subscripts subscript(_: Index) Required Declaration subscript(_i: Index) -> _Element { get }