Map, CompactMap, FlatMap

Comparing these functions

Source

1. Map

Using a transformation closure, we may transform arrays (and indeed any kind of collection) with the map() method. Your changed items will be contained in an array of the same size as the return value.

• Convert digits of array to square of digit of array

let digits = [1,2,3,4] 
let squares = digits.map {$0 *…