On Apr 25, 2007, at 5:49 PM, Frank D. Engel, Jr. wrote:
What I want to do (ideally) is add a new NSTable on the same tab as
the one for A, which will list all of the "rows" from B, with
checkboxes next to them, such that rows in B related to the selected
row from the table for A will be checked, and they will be unchecked
otherwise (with the checkboxes clickable to change the relationships).
[...]
Even better, could someone give me at least a sketchy outline with
the steps to set this up (or some similarly functional interface)?
The data source for the relationship table for view must, obviously,
know what is the currently-selected item (or are the currently-
selected items if you want to support that) in table A. Given that,
you can implement a data source for the relationship table view:
- (int)numberOfRowsInTableView:(NSTableView *)bTableView
{
return <number of objects of type B>;
}
- (id)tableView:(NSTableView *)bTableView
objectValueForTableColumn:(NSTableColumn *)bTableColumn
row:(int)rowIndex
{
if ([[bTableColumn identifier] isEqual:<anything except the
checkbox column identifier>])
{
return <the value appropriate for the row and column>;
}
if ([[bTableColumn identifier] isEqual:<the checkbox column
identifier>])
{
NSMangagedObject *moB = <instance of B at rowIndex>;
NSManagedObject *soA = <selected instance of A>
NSSet *relationshipSet = [soA valueForKey:@"relationshipName"];
BOOL b = [relationshipSet containsObject:moB];
return [NSNumber numberWithBool:b];
}
}
If you want to support a multiple selection in table view A, the
implementation will obviously be more sophisticated. You'll have to
iterate through the selected objects and determine whether moB is a
member of the relationship for each of them. If it is for all, return
NSOnState; if it is not for all, return NSOffState; if it is mixed,
return NSMixedState (wrapped in an NSNumber in each case).
The implementation of tableView:setObjectValue:forTableColumn:row:
follows the same pattern, except if the passed-in object's value is 1
then add moB to the relationship if it is absent, and if the passed-in
object's value is 0, then remove moB from the relationship if it is
present.
mmalc
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