title: Saving an email consent doc in researchkit (swift 3.1)
body: <p>i would like to be able to save and email a pdf of a consent form from research kit.  Currently, I have the following code to generate the pdf</p>
  
  <pre><code>let signatureResult : ORKConsentSignatureResult = taskViewController.result.stepResult(forStepIdentifier: "ConsentReviewStep")?.firstResult as! ORKConsentSignatureResult
  
  let consentDocument = ConsentDocument.copy() as! ORKConsentDocument
  signatureResult.apply(to: consentDocument)
  
  consentDocument.makePDF { (data, error) -&gt; Void in
  
      var documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
      documentsPath.append("consent.pef")
      var documentsURL = NSURL.fileURL(withPath: documentsPath)
  
      try? data?.write(to: documentsURL, options: [.atomic])
  }
  </code></pre>
  
  <p>This first fails with error Terminating app due to uncaught exception 'NSObjectNotAvailableException', reason: 'Signature title is missing'  </p>
  
  <p>Not sure where to go from here to get this part working, before moving on to the mailing function.</p>