Check if string is palindrome Swift 3

checkIfPalindrome.swift

func isPalindrome(_ word: String) -> Bool {
    let word = word.lowercased().characters.filter{ $0 != " " }
    for (i, character) in word.enumerated() {
        if character != word[word.count-i-1] {
            return false
        }
    }
    return true
}

While loop implementation:

extension StringProtocol {
  subscript(_ offset: Int) -> Element { self[index(startIndex, offsetBy: offset)] }
}

func isPalindrome(_ input: String) -> Bool {
  guard input.count > 1 else { return true }
  var lhs = 0; var rhs = input.count - 1

  while lhs < rhs {
    guard input[lhs] == input[rhs] else { return false }

    lhs += 1; rhs -= 1
  }

  return true
}

Anybody suggest how can achieve using high order func i.e Map or any ?