title: Swift compiler error: Cannot invoke 'lockForConfiguration' with an argument list of type '(() -> ())'
body: <p>This is Swift 2. I can't seem to find anything on this. I am getting the error </p>
  
  <pre><code>Cannot invoke 'lockForConfiguration' with an argument list of type '(() -&gt; ())'
  </code></pre>
  
  <p>On the second line here.</p>
  
  <pre><code>if let device = captureDevice {
              device.lockForConfiguration() {
                  device.videoZoomFactor = 1.0 + CGFloat(ratioValue)
                  device.unlockForConfiguration()
          }
          print(ratioValue)
      }
  </code></pre>