[Collection+subscript] Returns the element at the index if it is within range, otherwise `nil` #extension #iOS

Collection+subscript.swift

//
//  Collection+subscript.swift
//
//  Created by Jay Lee on 08/04/2019.
//  Copyright © 2019 Jay Lee <jaeho.lee@snu.ac.kr>
//  This work is free. You can redistribute it and/or modify it under the
//  terms of the Do What The Fuck You Want To Public License, Version 2,
//  as published by Sam Hocevar. See http://www.wtfpl.net/ for more details.
//

import Foundation

extension Collection {
  /// Returns the element at the index if it is within range, otherwise `nil`
  subscript (safe index: Index) -> Element? {
    return indices.contains(index) ? self[index] : nil
  }
}