> On Jan 29, 2010, at 9:38 AM, Jerry Krinock wrote:
>
>>
>> The problem is that when a subclass A is selected, the UI elements bound to
>> subclass B no longer have valid bindings so generate an error. How can I
>> solve this?
>
> You can also uncheck the "Raises For Not Applicable Keys" in the bindings
> inspector pain in Interface Builder for your text fields.
Thanks for the tip. Once I read it, it seemed like the logical solution.
However, it doesn't seem to make any difference. All I could find in the
documentation about that checkbox/attribute was:
NSRaisesForNotApplicableKeysBindingOption
An NSNumber object containing a Boolean value that specifies if an exception is
raised when the binding is bound to a key that is not applicable—for example
when an object is not key-value coding compliant for a key.
To recall, I have something like this:
@interface TopClass : NSObject
{
// some ivars
}
// some accessors
@end
@interface SubClass : TopClass
{
NSString* subValue;
}
- (NSString) subValue;
@end
I have an NSTreeController that contains a list of TopClass and SubClass items.
The user selects an item in that list.
I have a text field in Interface Builder whose value is bound (ie via bindings)
to the subValue accessor, ie: NSTreeController -> selection.subValue
Obviously, the subValue accessor is only valid if the currently selected item
is a SubClass object. If the user selects a TopClass item, it throws an
exception. How can I prevent this?
Thanks,
Tom
BareFeet
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