title: How do I check if a String includes a specific Character?
body: <p>How do I check if a <code>String</code> includes a specific <code>Character</code>?</p>
  
  <p>For example:</p>
  
  <pre><code>if !emailString.hasCharacter("@") {
      println("Email must contain at sign.")
  }
  </code></pre>