On Oct 17, 2009, at 7:40 PM, Ian Piper wrote:
I have a Core Data entity that has an attribute called charge
(stored as a float). So I am storing a number of records each of
which has a charge. I simply want to be able to show a running total
of charges as I add or remove items. I was hoping that I might be
able to use a simple binding for this: I created a label and thought
I might be able to bind its value to array
controller.arrangedObjects.charge.sum or something like that. No
luck though.
I cannot see anything in the documentation or from searches. Can
anyone point me towards either examples or documentation?
You want set and array operators:
http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/KeyValueCoding/Concepts/ArrayOperators.html
You really should read the KVC, KVO, Bindings, and Core Data guides
front to back since there are terms you wouldn't otherwise know to
search for. It's best to know you read about something but forget the
specifics then to not read it at all and have no idea. :-)
--
I.S.
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