On May 3, 2013, at 1:29 AM, Gerriet M. Denkmann <gerr...@mdenkmann.de> wrote: > I have a button which only makes sense when exactly one thing is selected. > Currently it's Enabled property is bound to Array > Controller.selectedObjects.@count. > I.e. the button is enabled if one or more things are selected. > > But I want it to be disabled when nothing is selected AND also if more than > one thing is selected. > Is there a way to do this without code? > > If not - what to do ? Create a value transformer? Or what else?
I vaguely remember doing this by adding a readonly property to the array controller -- something like "exactlyOneIsSelected" -- with a corresponding getter method. Then you can bind to ArrayController.exactlyOneIsSelected. Then the question would be how to trigger KVO on that property. I don't remember what I did. My first thought would be to implement +(NSSet *)keyPathsForValuesAffectingExactlyOneIsSelected, but I'm not sure what to return. Maybe @"selectionIndexes"? Would @"selectedObjects.@count" work? I don't know if you can use aggregation in keyPaths...Affecting... methods. It might be useful to implement these methods on a category of NSArrayController if you need this logic in multiple places. As usual I have a nagging feeling there's a better way, but this at least should work. --Andy _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
