Generic Instance Method

map(_:)

Returns an array containing the results of mapping the given closure over the sequence’s elements.

Declaration

func map<T>(_ transform: (Element) throws -> T) rethrows -> [T]

Parameters

transform

A mapping closure. transform accepts an element of this sequence as its parameter and returns a transformed value of the same or of a different type.

Return Value

An array containing the transformed elements of this sequence.

Discussion

In this example, map is used first to convert the names in the array to lowercase strings and then to count their characters.

let cast = ["Vivien", "Marlon", "Kim", "Karl"]
let lowercaseNames = cast.map { $0.lowercaseString }
// 'lowercaseNames' == ["vivien", "marlon", "kim", "karl"]
let letterCounts = cast.map { $0.characters.count }
// 'letterCounts' == [6, 6, 3, 4]