title: Swift 2 syntax error: Cannot call value of non-function type 'Int'
body: <p>I write a function:</p>
  
  <pre><code>extension String {
      func size()-&gt;Int{
          return count(self.utf16)
      }
  }
  </code></pre>
  
  <p>but it returns me an error:</p>
  
  <pre><code>Cannot call value of non-function type 'Int'
  </code></pre>
  
  <p>How can I fix it?</p>