title: How to find all positions of one string in another string in swift2 ?
body: <p>I can find first position of string "ATG" in myString "ATGGACGTGAGCTGATCGATGGCTGAAATGAAAA" (i.e. index range is 0..&lt;3) by using code below. Question is how to find all positions of "ATG", not only the first one in the myString. </p>
  
  <pre><code>let stringRange = myString.rangeOfString("ATG")
  </code></pre>