Returns an array containing the results of mapping the given closure over the sequence’s elements.
SDK
- Xcode 10.0+
Framework
- Swift Standard Library
Declaration
func map<T>(_ transform: (Self.Element) throws -> T) rethrows -> [T]
Parameters
transformA mapping closure.
transformaccepts 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.lowercased() }
// 'lowercaseNames' == ["vivien", "marlon", "kim", "karl"]
let letterCounts = cast.map { $0.count }
// 'letterCounts' == [6, 6, 3, 4]
Complexity: O(n), where n is the length of the sequence.