Instance Method

formIndex(_:offsetBy:)

Offsets the given index by the specified distance.

Declaration

func formIndex(_ i: inout Self.Index, offsetBy distance: Int)

Parameters

i

A valid index of the collection.

distance

The distance to offset i. distance must not be negative unless the collection conforms to the BidirectionalCollection protocol.

Discussion

The value passed as distance must not offset i beyond the bounds of the collection.

Complexity: O(1) if the collection conforms to RandomAccessCollection; otherwise, O(k), where k is the absolute value of distance.

See Also

Manipulating Indices

var startIndex: Self.Index

The position of the first element in a nonempty collection.

Required.

var endIndex: Self.Index

The collection’s “past the end” position—that is, the position one greater than the last valid subscript argument.

Required.

var indices: Self.Indices

The indices that are valid for subscripting the collection, in ascending order.

Required. Default implementation provided.

func index(after: Self.Index) -> Self.Index

Returns the position immediately after the given index.

Required.

func formIndex(inout Self.Index, offsetBy: Int, limitedBy: Self.Index) -> Bool

Offsets the given index by the specified distance, or so that it equals the given limiting index.