title: Obj/C: Sorting an array on a custom order
body: <p>I've got an array of NSMutableDictionaries, containing (amongst others) the key Location. 
  I need to sort the array to input it into a table. On top should be N, below should be A, and below that should be R.
  So in sort: How can I sort an array in the order: N - A - R?</p>
  
  <p>EDIT: I can order by looking at two variables, but I'm using more then 2 variables (7 in total)...</p>
  
  <p>Thanks,</p>