title: Make struct Hashable?
body: <p>I'm trying to create a dictionary of the sort <code>[petInfo : UIImage]()</code> but I'm getting the error <code>Type 'petInfo' does not conform to protocol 'Hashable'</code>. My petInfo struct is this:</p>
  
  <pre><code>struct petInfo {
      var petName: String
      var dbName: String
  }
  </code></pre>
  
  <p>So I want to somehow make it hashable but none of its components are an integer which is what the <code>var hashValue: Int</code> requires. How can I make it conform to the protocol if none of its fields are integers? Can I use the <code>dbName</code> if I know it's going to be unique for all occurrences of this struct?</p>