User Profile

Hi,The WWDC 2017 Whats New in Foundation says this functionality is coming soon. However XCode 9 has full complier support for this new syntax. I am trying to understand if this should work, or is not yet released?Any thoughts on why the followinig does not work?@objcMembers class Thing : NSObject { dynamic var stuff : String = ""}let thing = Thing()let observation = thing.observe(\Thing.stuff) { (model, change) in // This closure never gets called!}thing.stuff = "New Stuff"thing.stuff = "More New Stuff"Do I need to write via keyPath values (i.e. thing[keyPath: \.stuff] = "New Stuff" ) ?Thanks,Andrew