title: Main Queue Async vs. Default Queue Async Explanation
body: <p>I just watched this <a href="https://www.raywenderlich.com/3648-ios-concurrency-with-gcd-and-operations/lessons/2" rel="nofollow noreferrer">raywenderlich.com video</a> and took <a href="https://imgur.com/a/3pWLdVt" rel="nofollow noreferrer">this screenshot</a> of the code in question (@ 22:30).</p>
  
  <p>I'm wondering how <code>mainQueue.async</code> finished after <code>defaultQueue.async</code> despite being put on what I thought was a higher priority queue (defaulting to <code>userInteractive</code> or <code>userInitiated</code>, but regardless higher than <code>default</code>, right?). I watched the entire video and felt like I had a great grasp on everything until seeing that. Would anyone please be able to explain? Thanks so much in advance.</p>