title: Animation not working when disappearing, but works when appearing
body: <p>I'm trying to make a button appear and disappear (animated). When appearing, it animates. But when the button is supposed to disappear it doesn't animate, it just goes away.</p>
  <p>anybody any idea why when it appears it animates, but when it disappears it doesn't?</p>
  <p>Then button appears when a switch is turned on and disappears when the switch is turned off again.</p>
  <pre class="lang-swift prettyprint-override"><code>if switchesEnabled &gt; 0 {
       UIView.transition(with: button, duration: 0.25, options: .transitionCrossDissolve, animations: {self.button.isHidden = true})
  } else {
       UIView.transition(with: button, duration: 0.25, options: .transitionCrossDissolve, animations: {self.button.isHidden = false})
  }
  </code></pre>
  <p>additionally: the button also disappears when the button itself is pressed and, using exactly the same line of code, in that case it works.</p>