title: InvalidFirebaseData error when saving multiple values in Firebase
body: <p>The following code once worked fine and I was able to save multiple values to a Firebase record. However this no longer works since upgrading to Swift 3 (Xcode 8). I now get the following error:</p>
  
  <pre><code>*** Terminating app due to uncaught exception 'InvalidFirebaseData', reason: '(setValue:) Cannot store object of type _SwiftValue at mood. Can only store objects of type NSNumber, NSString, NSDictionary, and NSArray.'
  </code></pre>
  
  <p>The above error always mentions the second value, regardless of what type it is (even if it is one of the supported types like NSString). Here's what I have:</p>
  
  <pre><code>postsRef.childByAutoId().setValue(["postedBy": self.currentUser?.uid, "mood": mood, "status": status, "date": convertedDate])
  </code></pre>
  
  <p>This still seems to comply with the docs on the Firebase website. What am I doing wrong?</p>
  
  <p>Thanks!</p>