title: Check if NSString contains all or some characters
body: <p>I have an NSString called <code>query</code> which contains ~10 characters. </p>
  
  <p>I would like to check to see if a second NSString called <code>word</code> contains all of the characters in <code>query</code>, or some characters, but no other characters which aren't specified in <code>query</code>.</p>
  
  <p>Also, if there is only one occurrence of the character in the query, there can only be one occurrence of the character in the word.</p>
  
  <p>Please could you tell me how to do this?</p>
  
  <pre><code>NSString *query = @"ABCDEFJAKSUSHFKLAFIE";
  NSString *word  = @"fearing"; //would pass as NO as there is no 'n' in the query var.  
  </code></pre>