title: How to save coordinates to Firebase Swift 2
body: <p>I want to save a set of latitude and longitude coordinates to Firebase, but whenever my app runs through this code it crashes!</p>
  
  <pre><code>let userID: String = (FIRAuth.auth()?.currentUser?.uid)!
  let lat: Double = (locationManager.location?.coordinate.latitude)!
  let lon: Double = (locationManager.location?.coordinate.longitude)!
  
  self.ref.child("Location").child(userID).setValue(["Latitude": lat, "Longitude": lon])
  </code></pre>
  
  <p>Is there anyway I can fix this and save it properly and efficiently?</p>