title: "NSArray' does not have a member named 'append'
body: <p>I just got into swift coding and I am trying to follow a tutorial. but it seems as if the coder I'm following may have an older version, or I am doing something wrong. I am trying to make a sound object to make a soundboard. but when i try to add the sound file to the array using append, it says that the method <code>append</code> is not a member of the <code>NSArray</code>. can someone tell me what is the right way to do solve this?!]<a href="https://i.stack.imgur.com/3leoq.jpg" rel="noreferrer">1</a></p>
  
  <p><img src="https://i.stack.imgur.com/3leoq.jpg" alt="enter image description here"></p>