Cocoa Programming for OS X: The Big Nerd Ranch Guide

Create Names for the Defaults

You will be registering factory defaults, writing user preferences for defaults, and reading values for defaults, all based on a string that names each default. You will define a constant string for each of the default names.

At the top of PreferenceManager.swift, above the PreferenceManager, add the following constants:

i​m​p​o​r​t​ ​F​o​u​n​d​a​t​i​o​n​

p​r​i​v​a​t​e​ ​l​e​t​ ​a​c​t​i​v​e​V​o​i​c​e​K​e​y​ ​=​ ​"​a​c​t​i​v​e​V​o​i​c​e​"​
p​r​i​v​a​t​e​ ​l​e​t​ ​a​c​t​i​v​e​T​e​x​t​K​e​y​ ​=​ ​"​a​c​t​i​v​e​T​e​x​t​"​

c​l​a​s​s​ ​P​r​e​f​e​r​e​n​c​e​M​a​n​a​g​e​r​ ​{​

Why define constants that simply contain a fixed string? After all, you could just remember what the string was and type it in whenever ...