title: "switch(error!.code)" in canEvaluatePolicy function does not exist in Swift 3 (Xcode 8)
body: <p>I'm converting below code to Swift 3.</p>
  
  <pre><code> if context.canEvaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics, error:nil) {
  
    // 2.
    context.evaluatePolicy(LAPolicy.DeviceOwnerAuthenticationWithBiometrics,
      localizedReason: "Logging in with Touch ID",
      reply: { (success : Bool, error : NSError? ) -&gt; Void in
  
        // 3.
        dispatch_async(dispatch_get_main_queue(), {
          if success {
            self.performSegueWithIdentifier("dismissLogin", sender: self)
          }
  
          if error != nil {
  
            var message : NSString
            var showAlert : Bool
  
            // 4.
            switch(error!.code) {
  </code></pre>
  
  <p>Step 4 does not work anymore on Xcode 8, Swift 3. So I could not do the following cases:</p>
  
  <pre><code>switch(error!.code) {
            case LAError.AuthenticationFailed.rawValue:
              message = "There was a problem verifying your identity."
              showAlert = true
              break;
  </code></pre>
  
  <p>Currently, it's seems there was no solution that I could find yet. Any suggestion, please let me know.</p>
  
  <p>Thanks a lot!</p>