title: enum of string type vs struct with static constant
body: <p>It seems like when the need to use enum (of string type) arise, it can also be achieved using struct using static fields.</p>
  
  <p>e.g.</p>
  
  <pre><code>enum Test: String {
    case TestCase1
    case TestCase2
    case TestCase3
  }
  </code></pre>
  
  <p>or</p>
  
  <pre><code>struct Test {
    static let TestCase1 = "TestCase1"
    static let TestCase2 = "TestCase2"
    static let TestCase3 = "TestCase3"
  }
  </code></pre>
  
  <p>When is the enum approach preferred over the other, or vice versa?</p>