Kevin Muldoon wrote:
I have an NSTable which receives its dataSource from
MyTableController.m. However, my AppController.m needs the data
MyTableController.m holds. Since AppController.m hasn't explicitly
instantiated MyTableController (MyTableController being an NSObject
within IB with appropriate delegates and such) how does
AppController.m access MyTableController.m data? Thanks for the help.
How many MyTableController instances will there be at once?
If it's one, then you can use a Singleton pattern rooted in
AppController. Simply make AppController own and manage the data
source object (i.e. the Model for the table's View). AppController
is already a singleton (presumably), so giving it the responsibility
for other application-wide singletons isn't crazy. MyTableController
then calls on the single AppController instance to obtain the data
source object.
If there are multiple MyTableController instances at once, then you
can have them register themselves with the single AppController when
they are opened, and also unregister when closed. AppController
maintains a collection of these, and depending on which table data
source it wants, uses some mechanism to identify the corresponding
MyTableController. An example mechanism might be sequence number (1,
2, 3), name, etc. stored as keys in a dictionary, where the value is
the MyTableController instance.
You can use the register/unregister approach if there's a single
MyTableController, too, but it's more complex, and there's no need
when a perfectly good Singleton relationship will work.
-- GG
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