title: CFDictionary get Value for Key in Swift3
body: <p>I've a problem with accessing a specific (or any) key in a CFDictionary. 
  Honestly I don't really get the way you need to do this in Swift and I think it's overly complicated...</p>
  
  <p>My Code:</p>
  
  <pre><code>if let session = DASessionCreate(kCFAllocatorDefault) {
  let mountedVolumes = FileManager.default.mountedVolumeURLs(includingResourceValuesForKeys: [], options: [])!
  for volume in mountedVolumes {
      if let disk = DADiskCreateFromVolumePath(kCFAllocatorDefault, session, volume as CFURL) {
          let diskinfo = DADiskCopyDescription(disk);   
  
          var volumeValue = CFDictionaryGetValue(diskinfo, &lt;#T##key: UnsafeRawPointer!##UnsafeRawPointer!#&gt;)
  
  
      }
  }
  </code></pre>
  
  <p>What I want to achieve: Get the Value for the Key or field <em>DAVolumeNetwork</em> into the variable <em>volumeValue</em>.
  I guess I need to pass the <em>kDADiskDescriptionVolumeNetworkKey</em> to the <em>CFDictionaryGetValue</em> Method? How do I achieve this?</p>