Cocoa Programming for OS X: The Big Nerd Ranch Guide

Writing the Preferences to User Defaults

Now, add setters for the activeVoice and activeText properties. You will use each setter to store the user’s preferred value for that preference.

    var activeVoice: String? {
        set (newActiveVoice) {
            userDefaults.setObject(newActiveVoice, forKey: activeVoiceKey)
        }
        get {
            return userDefaults.objectForKey(activeVoiceKey) as? String
        }
    }

    var activeText: String? {
        set (newActiveText) {
            userDefaults.setObject(newActiveText, forKey: activeTextKey)
        }
        get {
            return userDefaults.objectForKey(activeTextKey) as? String
        }
    }