On 07/12/2011, at 7:35 AM, Geoffrey Holden wrote: > My apologies for subjecting you all to such a dim question - but I'm coming > back to cocoa programming after a bit of a lay off and I can't remember what > to do! > > I have a nib (xib - sorry) with my interface nicely laid out but I want it to > be updated by two classes. The class which is hooked up to first responder > is able to update its UI elements with no problem, but the other class > doesn't update its UI element at all. I can see in debug that the right > functions are executing - but the UI isn't getting updated. > > As far as I can see I've hooked everything up correctly. > > Please someone, nudge my memory. What have I forgotten?
Hard to say, but it sounds as if you've attempted to connect the same control to more than one outlet, which is impossible. The usual design is that there will exist a controller which handles a set of related UI elements. For example, if the elements are all part of a dialog panel, then the window controller for that panel will have outlets to each control, and an action method to respond to each control. It is the controller that then a) invokes model changes according to what controls the user interacted with and b) provides an interface to the rest of the app that changes the controls in response to data model changes. Bindings can automate this to a degree, but for a beginner is a pretty big chunk of behaviour to get one's head around, so probably best to stick with the relatively simple target/action approach at first. So rather than try to link your controls directly to objects that implement the data model, use a controller as an intermediary and have everything go through that. A typical way for a controller to update its controls when the model state changes is for it to receive notifications from the model, either classic NSNotificationCenter ones, or through the use of KVO, which is what bindings uses. Then, when a change is made to the model, no matter where it comes from, the UI reflects the change. If you find yourself writing code in your model that is setting control states to reflect its internal state, you've done it very, very wrong. hth, Graham_______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
