title: Use of increment operator gives build error "swift Unary operator '++' cannot be applied to an operand of type 'Int'"
body: <p>In the section <a href="https://developer.apple.com/library/ios/documentation/Swift/Conceptual/Swift_Programming_Language/BasicOperators.html">Basic Operators</a>, the Swift Programming Language guide states that ++ is a valid operator:</p>
  
  <blockquote>
    <p>“More complex examples include the logical AND operator &amp;&amp; (as in if
    enteredDoorCode &amp;&amp; passedRetinaScan) and the <strong>increment operator ++i</strong>,
    <strong>which is a shortcut to increase the value of i by 1</strong>.”</p>
  </blockquote>
  
  <p>Excerpt From: Apple Inc. “The Swift Programming Language.” iBooks. <a href="https://itun.es/gb/jEUH0.l">https://itun.es/gb/jEUH0.l</a> </p>
  
  <p>However, when attempting this in a playground;</p>
  
  <pre><code>import UIKit
  
  let i = 0
  i++
  </code></pre>
  
  <p>A build error shows:</p>
  
  <p><strong>swift Unary operator '++' cannot be applied to an operand of type 'Int'</strong></p>
  
  <p>Why?</p>