title: Negate #available statement
body: <p>I want to execute a code block only on devices running with an OS older than <code>iOS8</code>. I can't do:</p>
  
  <pre><code>if #available(iOS 8.0, *) == false {
      doFoo() 
  }
  </code></pre>
  
  <p>The solution I'm using for now is:</p>
  
  <pre><code>if #available(iOS 8.0, *) { } else { 
      doFoo() 
  }
  </code></pre>
  
  <p>, but it feels clunky. Is there another way to negate the <code>#available</code> statement elegantly with Swift ?</p>