title: How to convert "Index" to type "Int" in Swift?
body: <p>I want to convert the index of a letter contained within a string to an integer value. Attempted to read the header files but I cannot find the type for <code>Index</code>, although it appears to conform to protocol <code>ForwardIndexType</code> with methods (e.g. <code>distanceTo</code>).</p>
  
  <pre><code>var letters = "abcdefg"
  let index = letters.characters.indexOf("c")!
  
  // ERROR: Cannot invoke initializer for type 'Int' with an argument list of type '(String.CharacterView.Index)'
  let intValue = Int(index)  // I want the integer value of the index (e.g. 2)
  </code></pre>
  
  <p>Any help is appreciated.</p>