title: How to truncate decimals to x places in Swift
body: <p>I have a really long decimal number (say <code>17.9384693864596069567</code>) and I want to truncate the decimal to a few decimal places (so I want the output to be <code>17.9384</code>). I do <strong>not</strong> want to round the number to <code>17.9385</code>.</p>
  <p>How can I do this?</p>