title: Remove special characters from the string
body: <p>I am trying to use an iOS app to dial a number. The problem is that the number is in the following format: </p>
  
  <blockquote>
    <p>po placeAnnotation.mapItem.phoneNumber!<br>
    "‎+1 (832) 831-6486"</p>
  </blockquote>
  
  <p>I want to get rid of some special characters and I want the following:</p>
  
  <blockquote>
    <p>832-831-6486</p>
  </blockquote>
  
  <p>I used the following code but it did not remove anything: </p>
  
  <pre><code>let charactersToRemove = CharacterSet(charactersIn: "()+-")
  var telephone = placeAnnotation.mapItem.phoneNumber?.trimmingCharacters(in: charactersToRemove)
  </code></pre>
  
  <p>Any ideas?</p>