title: JSONSerialization Invalid type in JSON write (_SwiftValue)
body: <p>Why does the following code give me the error:</p>
  
  <blockquote>
    <p>Invalid type in JSON write (_SwiftValue).</p>
  </blockquote>
  
  <p>The error is thrown on this line:</p>
  
  <pre><code>urlRequest.httpBody = try JSONSerialization.data(withJSONObject: parameters)
  </code></pre>
  
  <p>Full code:</p>
  
  <pre><code>let parameters:Parameters = ["resource":[
          [
              "appUserCode":uuidString,
              "productNFCode": self.nfCode!,
              "status":code,
              "applicationKey":appDelegate.api_key
          ]
          ]
      ]
      do {
  
          urlRequest.httpBody = try JSONSerialization.data(withJSONObject: parameters)
      } catch {
          // No-op
      }
  </code></pre>