title: How to convert DispatchTimeInterval to NSTimeInterval (or Double)?
body: <p>I need to subtract a <a href="https://developer.apple.com/documentation/dispatch/dispatchtimeinterval" rel="noreferrer"><code>DispatchTimeInterval</code></a> from an <a href="https://developer.apple.com/documentation/foundation/nstimeinterval" rel="noreferrer"><code>NSTimeInterval</code></a> (or <code>Double</code>).</p>
  
  <p>Is there a standard way to convert a <code>DispatchTimeInterval</code> to an <code>NSTimeInterval</code>?</p>