title: Split NSString to array by specific word
body: <p>I need to split <code>NSString</code> to array by specific word.</p>
  
  <p>I've tried to use <code>[componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@" "]]</code></p>
  
  <p>But the split is performed by a single character, and I need a few chars.</p>
  
  <p>Example:</p>
  
  <pre><code>NSString @"Hello great world";
  </code></pre>
  
  <p>Split key == @" great ";</p>
  
  <p>result:</p>
  
  <pre><code>array[0] == @"Hello";
  array[1] == @"world";
  </code></pre>