title: What is the Swift equivalent of respondsToSelector?
body: <p>I've googled but not been able to find out what the swift equivalent to <code>respondsToSelector:</code> is.</p>
  
  <p>This is the only thing I could find (<a href="https://stackoverflow.com/questions/24142906/swift-alternative-to-respondstoselector">Swift alternative to respondsToSelector:</a>) but isn't too relevant in my case as its checking the existence of the delegate, I don't have a delegate I just want to check if a new API exists or not when running on the device and if not fall back to a previous version of the api.</p>