title: Create index for UITableView from an NSArray
body: <p>I've read that the best way of creating an index (the a-z at the side of a uitableview) is to set up an array of nsdictionaries, where each dictionary corresponds to a section, and a rowValue key contains an array of the rows.</p>
  
  <pre><code>NSDictionary
      headerTitle =&gt; ‘A’
      rowValues =&gt; {”Aardvark”, “Ape”, “Aquaman”}
  NSDictionary
      headerTitle =&gt; ‘B’
      rowValues =&gt; {”Bat”, “Boot”, “Bubbles”} etc
  </code></pre>
  
  <p>But how can this be created from an array of all the row titles - {”Aardvark”, “Ape”, “Aquaman”, ”Bat”, “Boot”, “Bubbles”, "Cat", "Cabbage" etc} ...?</p>