swift array map example
swift 5 // taken from developer.apple.com map(_:) 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]