Subscript

subscript(_:)

Accesses a contiguous subrange of the collection’s elements.

Declaration

subscript(bounds: Range<Int>) -> Slice<Array<Element>> { get set }

Parameters

bounds

A range of the collection’s indices. The bounds of the range must be valid indices of the collection.

Discussion

The accessed slice uses the same indices for the same elements as the original collection. Always use the slice’s startIndex property instead of assuming that its indices start at a particular value.

This example demonstrates getting a slice of an array of strings, finding the index of one of the strings in the slice, and then using that index in the original array.

let streets = ["Adams", "Bryant", "Channing", "Douglas", "Evarts"]
let streetsSlice = streets[2 ..< streets.endIndex]
print(streetsSlice)
// Prints "["Channing", "Douglas", "Evarts"]"

let index = streetsSlice.firstIndex(of: "Evarts")    // 4
streets[index!] = "Eustace"
print(streets[index!])
// Prints "Eustace"

Complexity: O(1)

See Also

Accessing Elements

subscript(Int) -> Element

Accesses the element at the specified position.

var first: Element?

The first element of the collection.

var last: Element?

The last element of the collection.

subscript(Range<Int>) -> ArraySlice<Element>

Accesses a contiguous subrange of the array’s elements.

subscript<R>(R) -> ArraySlice<Element>
subscript<R>(R) -> ArraySlice<Element>

Accesses the contiguous subrange of the collection’s elements specified by a range expression.

subscript((UnboundedRange_) -> ()) -> ArraySlice<Element>
func randomElement() -> Element?

Returns a random element of the collection.

func randomElement<T>(using: inout T) -> Element?

Returns a random element of the collection, using the given generator as a source for randomness.