title: How can I produce an effect similar to the iOS 7 blur view?
body: <p>I'm trying to replicate this blurred background from Apple's publicly released iOS 7 example screen:</p>
  
  <p><img src="https://i.stack.imgur.com/whHSxm.jpg" alt="iOS 7 Control Center screenshot"></p>
  
  <p><a href="https://stackoverflow.com/questions/17036655/ios-7-style-blur-view">This question</a> suggests applying a CI filter to the contents below, but that's a whole different approach. It's obvious that iOS 7 doesn't capture the contents of the views below, for many reasons:</p>
  
  <ol>
  <li>Doing some rough testing, capturing a screenshot of the views below and applying a CIGaussianBlur filter with a large enough radius to mimic iOS 7's blur style takes 1-2 seconds, even on a simulator.</li>
  <li>The iOS 7 blur view is able to blur over dynamic views, such as a video or animations, with no noticeable lag.</li>
  </ol>
  
  <p>Can anyone hypothesize what frameworks they could be using to create this effect, and if it's possible to create a similar effect with current public APIs?</p>
  
  <p><strong>Edit:</strong> (from comment) We don't exactly know how Apple is doing it, but are there any basic assumptions we can make? We can assume they are using hardware, right? </p>
  
  <p>Is the effect self-contained in each view, such that the effect doesn't actually know what's behind it? Or must, based on how blurs work, the contents behind the blur be taken into consideration? </p>
  
  <p>If the contents behind the effect are relevant, can we assume that Apple is receiving a "feed" of the contents below and continuously rendering them with a blur? </p>