title: How do I filter on an array of objects in Swift?
body: <p>Hi I have an array of type Book objects and I'm trying to return all the Books filtered by the <code>tags</code> attribute. For example</p>
  
  <pre><code>var books = [
  
  (title = "The Da Vinci Code", tags = "Religion, Mystery, Europe"), 
  (title = "The Girl With the Dragon Tatoo", tags = "Psychology, Mystery, Thriller"), 
  (title = "Freakonomics", tags = "Economics, non-fiction, Psychology")
  
  }]
  </code></pre>
  
  <p>and I want to find the books associated with the tags <code>Psychology</code>, <code>(title = "The Girl With the Dragon Tatoo", tag = "Psychology, Mystery, Thriller")</code> and <code>(title = "Freakonomics", tags = "Economics, non-fiction, Psychology")</code>, how would I do that?</p>