Delete elements from an array

delete_elements.swift

//: Playground - noun: a place where people can play

import UIKit

// General Case for an Array
extension Array where Element:Hashable {
    mutating func deleteElements(_ elements:[Element]) -> ArraySlice<Element> {
        var toDelete: [Element: Bool] = [:]
        for e in elements {
            toDelete[e] = true
        }
        var dst = 0
        var src = 0
        for i in self {
            let found = toDelete[i, default: false]
            if !found {
                self[dst] = self[src]
                dst += 1
            }
            src += 1
        }
        return self[..<dst]
    }
}

var a = [1,2,3,4,5,6]
let ad = a.deleteElements([1,4])
assert(ad == [2, 3, 5, 6])

extension String {
    func deleteChars(_ chars: String) -> String {
        var stringArray = Array(self.lowercased())
        let lowercasedChars = chars.lowercased()
        let toDeleteArray = Array(lowercasedChars)
        let result = stringArray.deleteElements(toDeleteArray)
        let resultAsString = String(result)
        return resultAsString
    }
}

var str = "As Gregor Samsa awoke one morning from uneasy dreams he found himself transformed in his bed into an enormous insect."
let deleted = str.deleteChars("aeiou")
assert(deleted == "s grgr sms wk n mrnng frm nsy drms h fnd hmslf trnsfrmd n hs bd nt n nrms nsct.")