Random string generator in swift

RandomStringGenerator.swift

import Foundation
func randomStringGenerator(number : Bool, whiteSpace : Bool, specialCharacters : Bool,upperCase : Bool,  size : Int) -> String
{
    var returnString = ""
    let  specialCharactersArray : [Character] = [",","<",".","?",">","/","\"","|","[","]",";",":","\'","\"",]
    let numbers = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "0"]
    let letters = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]
    let uppercase = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]
     
    while(returnString.count != size){
         switch Int.random(in: 0 ... 5) {
         case 1: if(number) {returnString.append(numbers.randomElement()!) ;break}
         case 2: if(whiteSpace){returnString += " "; break}
         case 3 : if (specialCharacters){returnString.append(specialCharactersArray.randomElement()!); break}
         case 4 : if(upperCase){returnString.append(uppercase.randomElement()!); break}
        default:
            returnString.append(letters.randomElement()!)
        }
     }
    return returnString
}