Retrive the key code of macOS keyboard from the keys' names

String+KeyCode.swift

//
//  String+KeyCode.swift
//  Volcano-Maxhub
//
//  Created by David Lee on 2018/4/13.
//  Copyright © 2018年 MAXHUB. All rights reserved.
//
//  Thanks to this answer:
//  https://stackoverflow.com/questions/10734349/simulate-keypress-for-system-wide-hotkeys/13004403#13004403

import Foundation

extension String {
    var keyCode: CGKeyCode? {
        switch self {
        case "a": return 0
        case "s": return 1
        case "d": return 2
        case "f": return 3
        case "h": return 4
        case "g": return 5
        case "z": return 6
        case "x": return 7
        case "c": return 8
        case "v": return 9
        // what is 10?
        case "b": return 11
        case "q": return 12
        case "w": return 13
        case "e": return 14
        case "r": return 15
        case "y": return 16
        case "t": return 17
        case "1": return 18
        case "2": return 19
        case "3": return 20
        case "4": return 21
        case "6": return 22
        case "5": return 23
        case "=": return 24
        case "9": return 25
        case "7": return 26
        case "-": return 27
        case "8": return 28
        case "0": return 29
        case "]": return 30
        case "o": return 31
        case "u": return 32
        case "[": return 33
        case "i": return 34
        case "p": return 35
        case "RETURN": return 36
        case "l": return 37
        case "j": return 38
        case "'": return 39
        case "k": return 40
        case "": return 41
        case "\\": return 42
        case ",": return 43
        case "/": return 44
        case "n": return 45
        case "m": return 46
        case ".": return 47
        case "TAB": return 48
        case "SPACE": return 49
        case "`": return 50
        case "DELETE": return 51
        case "ENTER": return 52
        case "ESCAPE": return 53
            
            // some more missing codes abound, reserved I presume, but it would
            // have been helpful for Apple to have a document with them all listed
            
        case ".": return 65
            
        case "*": return 67
            
        case "+": return 69
            
        case "CLEAR": return 71
            
        case "/": return 75
        case "ENTER": return 76  // numberpad on full kbd
            
        case "=": return 78
            
        case "=": return 81
        case "0": return 82
        case "1": return 83
        case "2": return 84
        case "3": return 85
        case "4": return 86
        case "5": return 87
        case "6": return 88
        case "7": return 89
            
        case "8": return 91
        case "9": return 92
            
        case "F5": return 96
        case "F6": return 97
        case "F7": return 98
        case "F3": return 99
        case "F8": return 100
        case "F9": return 101
            
        case "F11": return 103
            
        case "F13": return 105
            
        case "F14": return 107
            
        case "F10": return 109
            
        case "F12": return 111
            
        case "F15": return 113
        case "HELP": return 114
        case "HOME": return 115
        case "PGUP": return 116
        case "DELETE": return 117
        case "F4": return 118
        case "END": return 119
        case "F2": return 120
        case "PGDN": return 121
        case "F1": return 122
        case "LEFT": return 123
        case "RIGHT": return 124
        case "DOWN": return 125
        case "UP": return 126
            
        default:
            print("Well, this is out of my reach.")
            return nil
        }
    }
}