title: Objective-C: Find consonants in string
body: <p>I have a string that contains words with consonants and vowels. How can I extract only consonants from the string?</p>
  
  <pre><code>NSString *str = @"consonants.";
  </code></pre>
  
  <p>Result must be:</p>
  
  <pre><code>cnsnnts
  </code></pre>