title: Check if a String is the current date
body: <p>I am new to swift and I would like to separate a string into an array. In my case the string is "20170227" and I would like to have it in an array like [2017,02,27]. I have tried doing this, but the code was way too long and I think by far to complicated for what it is. </p>
  
  <pre><code> var date = "20170227"
   var Space: Character = " "
   let indexMain = date.index(date.startIndex, offsetBy: 4)
   date.insert(Space, at: indexMain)
  </code></pre>
  
  <p>which eventually only returns 2017 0227, so I'm lost... Thanks in advance!</p>