title: add image to UIButton asynchronously
body: <p>I have the following situation</p>
  
  <pre><code>UIImage *btnImage = [UIImage imageNamed:@"image.png"];
  [btnTwo setImage:btnImage forState:UIControlStateNormal];
  </code></pre>
  
  <p>But for some reason it seems to be causing some delay in my code, so I want to execute these two lines asynchronously. How might I do that?</p>