title: 'bytes' is unavailable: use withUnsafeBytes instead
body: <p>Code that was previously working in Swift 2.2 is now throwing the following error in Swift 3:</p>
  
  <p><a href="https://i.stack.imgur.com/J0Ej0.png"><img src="https://i.stack.imgur.com/J0Ej0.png" alt="enter image description here"></a></p>
  
  <p>Here is my code:</p>
  
  <pre><code>let tempData: NSMutableData = NSMutableData(length: 26)!
  tempData.replaceBytes(in: NSMakeRange(0, data.count), withBytes:data.bytes)
  </code></pre>
  
  <p>What should I replace "data.bytes" with to fix the error?  I've tried implementing 'withUnsafeBytes' and had a look at Apple's documentation, but can't get my head around it!</p>