Scott Pugh thinks this is interesting: set the model key path to numberValue. From 11. Cocoa Bindings from Swift Development with Cocoa by Tim Nugent, Jonathon Manning, Paris Buttfield-Addison Publisher: O'Reilly Media, Inc. Released: December 2014 Note self.numberValue maybe? Share this highlight http://www.safaribooksonline.com/a/swift-development-with/61787/ Twitter Facebook Google Plus Email Get Instant Access Now Start a Free Trial Learn about Safari for Business Have an account? Sign in. Minimise Unlock the rest of Swift Development with Cocoa and 30,000 other books and videos By clicking this box, you confirm that you have read and agree to the terms and conditions of our Membership Agreement, and you understand that when your trial period ends, you will be required to provide billing information if you wish to continue using the service. Unlock the rest of this book Start a Free 10-Day Trial loading Learn about Safari for Business Have an account? Sign in.