title: Change MFMailComposeViewController's UINavigationBar color in iOS7
body: <p>I am trying to update my app for <code>iOS7</code>, however I am unable to set the colour of the <code>UINavigationBar</code> at the top of the screen. I have tried the classic approach...</p>
  
  <pre><code>[mailer.navigationBar setTintColor:[UIColor darkGreyColour]];
  </code></pre>
  
  <p>...however it didn't work. I have also tried calling <code>setBarTintColor</code> instead, however that didn't seem to work either.</p>
  
  <p>Does anyone know if its possible to set the colour and if so how?</p>