title: How to get substring with specific ranges in Swift 4?
body: <p>This is using the example code from the official Swift4 doc</p>
  
  <pre><code>let greeting = "Hi there! It's nice to meet you! "
  let endOfSentence = greeting.index(of: "!")!
  let firstSentence = greeting[...endOfSentence]
  // firstSentence == "Hi there!"
  </code></pre>
  
  <p>But lets say <code>let greeting = "Hello there world!"</code>
   and I want to <strong>retrieve only the second word</strong> (substring) in this sentence? So I only want the word "there".</p>
  
  <p>I've tried using "world!" as an argument like 
  <code>let endOfSentence = greeting.index(of: "world!")!</code> but Swift 4 Playground doesn't like that. It's expecting 'Character' and my argument is a string.</p>
  
  <p>So how can I get a substring of a very precise subrange? Or get nth word in a sentence for greater use in the future?</p>