||The Cocoa Controller Layer|
A minor error in your article. The Model Key Path is not just simply "the key used to access the property of the data model whose value we're interested in displaying". From the ADC web site, "A key path is a string of dot separated keys that is used to specify a sequence of object properties to traverse.". In other words, foo.bar.baz means get the baz property of the bar object in the foo object.