title: Measuring distance with iPhone camera
body: <p>How to implement a way to measure distances in real time (video camera?) on the iPhone, <a href="http://www.apptism.com/apps/rulerphone" rel="noreferrer">like this app</a> that uses a card to compare the size of the card with the actual distance?</p>
  
  <p>Are there any other ways to measure distances? Or how to go about doing this using the card method? What framework should I use?</p>