title: how to run code in the UI thread calling it from the others ones
body: <p>In Android there are several ways to run some code in the main thread from others ones:</p>
  
  <pre><code> 1. Activity.runOnUiThread(Runnable r)
   2. new Handler.post(Runnable r);
   3. View.post
  </code></pre>
  
  <p>What are the analogues in iOS?</p>
  
  <pre><code> dispatch_async(dispatch_get_main_queue(), ^{
  
      });
  </code></pre>
  
  <p>Something else?</p>
  
  <p>Thanks in advance.</p>