title: What happens when you run deprecated code in swift?
body: <p>For example in iOS 10 there's <code>UserNotifications</code> framework. Prior to that you just have to use: </p>
  
  <pre><code>let settings = UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
   application.registerUserNotificationSettings(settings)
   application.registerForRemoteNotifications()
  </code></pre>
  
  <p>(I ran the code above on iOS 10 and nothing happened).</p>
  
  <p>My generic question is: would running deprecated syntax crash all the time, just do nothing (as now) or how it treats is unknown?</p>
  
  <p>I'm asking to get a better debugging <em>understanding</em>. </p>