title: Change iOS7 Status Bar Colour programmatically, mid-run?
body: <p>I’m trying to change the Status Bar colour mid-run, i.e. not when a controller is loaded. I change the view’s background colour, so I need to change it from the black to white and vice versa.</p>
  
  <p>I know that I can change it using <code>preferredStatusBarStyle</code> and the setting in the plist, but as far as I can see that’ll only set it on first launching the view controller. I’d like to change it, for instance, when I hit a button.</p>
  
  <p>Can I do that?</p>