On Nov 28, 2009, at 14:45, David Hirsch wrote:
> My document class has an array of Instructors, with a controller. Each
> instructor has a timeConstraint, which in turn has an array of NSNumbers. I
> have an NSTableView bound to the Instructor array, and I would like to show
> the mondayCosts array of floats in another TableView, which will change when
> the selection in the instructor table changes. Below are bits of the
> headers. (I have @synthesized each of the properties in the implementation
> files)
>
> I can get the selection, including other fields of the selected Instructor.
> I've tried making another NSArrayController in IB with its content bound to
> instructorController.selection.timeConstraint.mondayCosts, and binding the
> table column to that, but even if that works, then it's not clear to me how
> to get the floats out of the NSNumbers.
>
> @interface ClassSchedulerDoc : NSDocument
> {
> IBOutlet NSArrayController *instructorController;
> NSMutableArray *instructors;
> }
>
>
> @interface Instructor : NSObject <NSCoding> {
> }
> @property (retain) ProfTimeConstraint *timeConstraint;
>
>
> @interface ProfTimeConstraint : Constraint {
> }
> @property (retain) NSMutableArray *mondayCosts; // floats within
> NSNumbers
As far as it goes, it looks like you're doing the right thing. The table column
can be bound to the MondayCosts NSArrayController, with either no model key, or
a model key of "self". (They mean the same thing.) You likely don't have to
"get the floats out of the NSNumbers" yourself:
If the table column has a plain text cell, then the value to be displayed will
be retrieve by sending a 'stringValue' message to the underlying NSNumber
object, which should come out as a properly formatted float.
If you don't like the standard formatting, you can add a numeric formatter to
the table column cell.
The limitation here is that this only works for *display* of the numbers -- you
can't edit them in the table because, with this binding, that would imply
modifying the NSNumber's "self" property, which makes no sense (and causes an
exception if you try). If you want the table to be editable, the easiest
solution is to create a class MondayConstraint (for example) which has a "cost"
property that is both gettable and settable. Your ProfTimeConstraint would then
have an array of MondayConstraint objects instead of an array of NSNumber
objects, and you'd bind the table column to the MondayCosts array controller
with key "cost".
HTH
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