title: Change the image of a specific button
body: <p>This is the first app I'm writing so this could be an easy question.
  I want to delete the image of a button with a tag.
  What I have is this line of code:</p>
  
  <pre><code>.setImage(UIImage(named: ""), for: UIControlState())
  </code></pre>
  
  <p>But what do I have to write in front of this line so I can "talk" to specific buttons?</p>