title: How to get the today's and tomorrow's date in swift 4
body: <p>How to get the current date in <code>unix-epoch</code>?
  <code>timeIntervalSince1970</code> prints the current time. Is there any way to get today's time at 12 AM?</p>
  
  <p>For example, The current time is : Jan 7, 2018 5:30 PM. <code>timeIntervalSince1970</code> will print the current time i.e. <code>1546903800000</code>. 
  Current date in epoch system will be Jan 7, 2018 00:00 AM. i.e <code>1546848000000</code> </p>