title: Adding NSTextFields together Swift 3 XCode 8
body: <p>Any anyone explain the syntax in adding two or more textfields together in Swift 3 inside XCode 8. This is for a desktop application, not IOS. NSTextField Control.</p>
  
  <p>I need precision to the tenth's place. So I guess a float will be necessary. </p>
  
  <p>Furthermore, how can I do the adding automatically when the textbox is updated, so it is adding on the fly. So I do not have to put in a "Calculate" button. Do I need to do anything special to sanitize the fields to prevent alphas to be typed?</p>