title: Number of occurrences of a substring in an NSString?
body: <p>How can I get the number of times an NSString (for example, <code>@"cake"</code>) appears in a larger NSString (for example, <code>@"Cheesecake, apple cake, and cherry pie"</code>)?</p>
  
  <p>I need to do this on a lot of strings, so whatever method I use would need to be relatively fast.</p>
  
  <p>Thanks!</p>