On Oct 18, 2010, at 10:22 AM, Trygve Inda wrote: >> So if the master dictionary and the array for the NSTable are >> encapsulated together in a class, you could use NSMutableArray as the >> primary structure, and encapsulate a hidden NSMutableDictionary used >> only for faster searching. Both are maintained in parallel by the >> enclosing class, so there's never any need to ask the dictionary for >> its array of values, nor to copy an immutable array to make a mutable >> version for table insertion. In short, make a class that >> encapsulates all the desired behavior by itself, rather than using a >> naked dictionary and the supplementary arrays it makes. > > How would I go about doing this and still bind to my NSArrayController? > > I'd have a (singleton) class MyDataClass with two instance vars: myArray and > myDictionary both of which would hold the same objects and both would be > mutable. > > So when I bind the NSArrayController to myArray, and the user adds an item > via the table (and thusly the add: of NSArrayController), how will my class > know that it needs to also add it to the myDictionary?
You are mistaking instance variables for properties. Instance variables are implementation details, and nothing outside of your class should be aware of them. Properties are part of your interface, essentially the accessor methods and their behavior. (Remember that you can have properties that are not backed by instance variables.) So, you should be thinking in terms of writing accessor methods which present a consistent view of the to-many relationship (which happens to be backed by an array and a dictionary). Look up the indexed accessor pattern for to-many relationships in the KVC documentation <http://developer.apple.com/library/mac/documentation/cocoa/Conceptual/KeyValueCoding/Concepts/AccessorConventions.html#//apple_ref/doc/uid/20002174-178830-BAJEDEFB>. Also, take a look at "Managing a non-array collection, and filtering" on mmalc's page of Cocoa examples <http://homepage.mac.com/mmalc/CocoaExamples/controllers.html>. To keep yourself honest, and to help you learn, try making this to-many relationship property have a name completely different from the names of the instance variables which back it. Also, I generally recommend that all of one's own classes should override +accessInstanceVariablesDirectly to return NO. (I regard KVC's ability to bypass your interface and directly access your instance variables as A Bad Thing™.) Regards, Ken _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
