title: Check if tintColor is dimmed in tintColorDidChange
body: <p>On iOS 7, when the tint color changes (for example, when a UIAlertView is presented), views are notified in their <code>tintColorDidChange</code> method.</p>
  
  <p>I have a few subviews for which I'd like to provide a customized disabled state.  (For example, say I'd like to also temporarily dim the <code>backgroundColor</code> of a custom UIControl.)</p>
  
  <p>I had been using this code:</p>
  
  <pre><code>- (void)tintColorDidChange {
      BOOL isInactive = (CGColorSpaceGetModel(CGColorGetColorSpace([self.tintColor CGColor])) == kCGColorSpaceModelMonochrome);
      if (isInactive) {
          // modify subviews to look disabled
      } else {
          // modify subviews to look enabled
      }
  }
  </code></pre>
  
  <p>However, on some views in one of my apps, the <em>active</em> tint color is a very dark gray, and the <em>inactive</em> tint color is a lighter gray.</p>
  
  <p>In this case, both colors report as "inactive" because both colors are monochrome.</p>
  
  <p>Is there a better test to determine if the current state is active or dimmed?</p>