title: What level is the default level equal to, in DispatchQoS?
body: <p>The DispatchQoS structure, as does the DispatchQoS.QoSClass enumeration, defines a <code>default</code> quality of service.</p>
  
  <p>After looking at the Apple references, I still cannot figure out the level. Even when stopping it in the debugger and printing out the value, it only lists <code>default</code>.</p>
  
  <p>Command-clicking on the property in Xcode shows me this:</p>
  
  <pre><code>@available(OSX 10.10, iOS 8.0, *)
          case `default` 
  </code></pre>
  
  <p>The struct reference doesn't provide anything helpful:
  <a href="https://developer.apple.com/documentation/dispatch/dispatchqos" rel="nofollow noreferrer">https://developer.apple.com/documentation/dispatch/dispatchqos</a></p>
  
  <p>The enumeration reference is similar:
  <a href="https://developer.apple.com/documentation/dispatch/dispatchqos/qosclass" rel="nofollow noreferrer">https://developer.apple.com/documentation/dispatch/dispatchqos/qosclass</a></p>