OS X: Bindings, KVC, and KVO - Core Data - page 144

Figure 29— NSNumberFormatter Attributes inspector

Once an NSFormatter has been applied to an object, it can be a little tricky to
reference it again to make changes. To change or remove an NSFormatter once
it has been applied, select the number formatter in the element list on the
left side of the Interface Builder view. Selecting the line item references the
NSFormatter again so that it can be manipulated. See Figure 30, Accessing an
existing NSFormatter on an element , on page 148 .

8.4 Other Interface Elements That Use KVO, KVC, and Core Data

Although the previous sections show how to access the Core Data repository
in our recipe application with KVO and KVC, let's quickly review the other
elements that, if we wanted or needed to, could be utilized to display the data
in our application as well.

NSObjectController
NSObjectController shares a lot of similarities with the NSArrayController discussed
earlier. However, unlike the NSArrayController , the NSObjectController is designed to
represent one instance rather than an array of instances. A common usage
of the NSObjectController is to represent the selected object of an NSArrayController ,
thereby making it clearer as to what data is being displayed in the interface
elements that are bound to the NSObjectController , as opposed to an NSArrayController .
Another common usage is to have an entire interface, such as a detail sheet
or child window, be bound to the values within an NSObjectController and then
have the File's Owner reference and populate that NSObjectController . In this
design, the File's Owner (usually a subclass of NSWindowController ) simply has
to populate the NSObjectController with a call to -setContent: , and the entire UI is