title: How to convert CoreData Date to DateTime in Swift 3
body: <p>I have <code>CoreData</code> myDate = date, Entity column and returns output:</p>
  
  <pre><code>let mydate = coreDataValues[0].myDate!
  print(mydate)
  
  OUTPUT == 2017-02-01 12:45:40 +0000 
  </code></pre>
  
  <p>I want to convert <code>mydate</code> to <code>datetime</code> under below like , example ;</p>
  
  <pre><code>2017-12-20-23-59-59
  </code></pre>
  
  <p>How can I do it ?</p>
  
  <p>Ty</p>