title: CIDetector memory usage seems to be growing indefinitely
body: <p>I'm using <a href="https://developer.apple.com/library/ios/documentation/CoreImage/Reference/CIDetector_Ref/Reference/Reference.html" rel="nofollow noreferrer"><code>CIDetector</code></a> multiple times and memory usage is growing for every image in a project that uses ARC.</p>
  
  <pre><code>NSArray* features = [self.detector featuresInImage:ciimage options:detectorOptions];
  ...
  // some code dealing with features
  features = nil
  </code></pre>
  
  <p>I see in Instruments that ref count of <code>features</code> is always +1. I noticed that if added</p>
  
  <pre><code>self.detector = nil;
  </code></pre>
  
  <p>then memory goes down substantially and no listing of <code>FaceCore</code> in instruments.</p>
  
  <p><img src="https://i.stack.imgur.com/gK7cP.jpg" alt="enter image description here"></p>
  
  <p>Any way the face detector isn't releasing its memory?</p>