title: Checking if a thread (using GCD) exists or has finished
body: <p>I would like to be able to download some data from our server in the background after they log in. Is there a way I can set it up so when the user goes to that section of the program (say its downloading recipes), that I can check if there is a current download for a new recipe that hasn't saved yet? </p>
  
  <p>It would be nice if the user goes to recipes, and sees an indicator of some sort that it is currently downloading new recipes.</p>
  
  <p>Can I name the threads? Can I put all the "recipe" threads in stack and check if its empty or has a thread in it?</p>
  
  <p>I'm using GCD.</p>
  
  <p>Any ideas?</p>