Instance Property

indices

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

Required. Default implementation provided.

Declaration

var indices: Self.Indices { get }

Discussion

A collection’s indices property can hold a strong reference to the collection itself, causing the collection to be nonuniquely referenced. If you mutate the collection while iterating over its indices, a strong reference can result in an unexpected copy of the collection. To avoid the unexpected copy, use the index(after:) method starting with startIndex to produce indices instead.

var c = MyFancyCollection([10, 20, 30, 40, 50])
var i = c.startIndex
while i != c.endIndex {
    c[i] /= 5
    i = c.index(after: i)
}
// c == MyFancyCollection([2, 4, 6, 8, 10])

Default Implementations

Collection Implementations

var indices: DefaultIndices<Self>

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

Available when Indices is DefaultIndices<Self>.

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.

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

Returns the position immediately after the given index.

Required.

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

Offsets the given index by the specified distance.

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.