It's just saying that whatever data-model object that NSObjectController is using does't have an appropriate key method for that value.
From looking at the Cocoa Bindings Reference documentation, the value
binding should be set to a key in your NSObjectController that corresponds to a key-value-coding compliant key in its model.
Example:
NSObjectController
mode is Class
, Class Name is foo
. Then you bind foo's key of comboSelection
to the NSComboBox's value
. What the exception is saying is that the Foo class doesn't have a method called comboSelection
:
- (NSString*)comboSelection;
- (void)setComboSelection:(NSString*)inSelection;
In the case of using a NSMutableDictionary as the NSObjectController's class, it's much easier, since the dictionary can hold arbitrary keys.
If you're using CoreData (mode = Entity), then your CoreData entity must contain the appropriate property.