swift - How to return an subset of Array of characters?

Question

I am trying to dynamically chop an array of letters but I can't seem to reconvert the result back into a [String]

let letters:String = "abcdefghijklmnopqrstuvwxyz"
let lettersarray = Array(letters.characters)

var targetNum = 14 // Show just the first 14 characters

var resultsArray = [String]()

let resultsSlice = lettersarray.dropLast(lettersarray.count - targetNum) // Returns an Array Slice instead of an Array

let newresultsArray = Array(resultsSlice) // Returns Array<_element> instead of [String]

How do I return a [String] ie ["a","b","c"... eg]

Answer 1

You need to map the Character array back to String

let resultsArray = lettersarray.dropLast(lettersarray.count - targetNum).map{String($0)}

alternatively (credits to Leo Dabus)

let letters = "abcdefghijklmnopqrstuvwxyz"
let targetNum = 14
let resultsArray = letters.characters.prefix(targetNum).map{String($0)}