title: Sorting an NSArray of NSString
body: <p>Can someone please show me the code for sorting an NSMutableArray? I have the following NSMutableArray:</p>
  
  <pre><code>NSMutableArray *arr = [[NSMutableArray alloc] init];
  </code></pre>
  
  <p>with elements such as "2", "4", "5", "1", "9", etc which are all NSString.</p>
  
  <p>I'd like to sort the list in descending order so that the largest valued integer is highest in the list (index 0).</p>
  
  <p>I tried the following:</p>
  
  <pre><code>[arr sortUsingSelector:@selector(compare:)];
  </code></pre>
  
  <p>but it did not seem to sort my values properly. </p>
  
  <p>Can someone show me code for properly doing what I am trying to accomplish? Thanks!</p>