OS X: Bindings, KVC, and KVO - Core Data - page 147

thanks to KVO, any tables or interface elements associated with that NSArray-
Controller will get updated automatically and instantly. This means if we put a
search field into our application and link it to our NSArrayController of Recipe
objects, our source list of recipes will automatically be filtered based on the
user input into that NSSearchField . Even better, we don't have to write any code!
All we need to do to implement it is configure the bindings for the NSSearchField .
To accomplish this, we first add an NSSearchField to our application. In Figure
32, Adding an NSSearchField to our application , on page 150 , we have decreased
the vertical size of the recipe source list and inserted an NSSearchField above it.
Next, we configure its bindings.
Figure 32—Adding an NSSearchField to our application
As shown in Figure 33, NSSearchField bindings , on page 151 , the NSSearchField
interface element works with an NSPredicate . We write the predicate in the
Predicate Format field, substituting $value for whatever the user inputs into
the search field and using the controller key and value transformer to bind
it to our data. In this example, we want to filter on the name of recipes;
therefore, we bind the NSSearchField to our recipe's NSArrayController using the
controller key of filterPredicate and a predicate of namecontains[c]$value .
Once we add one predicate, another appears on the Bindings tab for the
NSSearchField . This is so we can use a search field for more than one type of
search. Each search will be shown in the drop-down on the NSSearchField , and
the Display Name binding will be shown to the user. This allows us to create
one NSSearchField that can search for recipe names, ingredients, descriptions,
or anything else we may need.
Once the binding is complete, we are done adding a basic search field. Running
the application shows that text entered into the search field impacts the list