An easy way to maintain UserDefaults key

You can use #function literal to get the property name as UserDefault key. In the following example, #function will get replaced by accessToken. Be aware, changing the property names may break functionality for the existing users.

extension UserDefaults {
    var accessToken: String? {
        get {
            return string(forKey: #function)
        }
        set {
            set(newValue, forKey: #function)
            synchronize()
        }
    }
}