Returns the object in the array with the given identifier.
- macOS 10.5+
The identifier of one of the receiver's objects.
A reference to the identified object or
nil if could not be found.
This method is provided as an alternative to
object for applications where an identifier is available instead of (or in addition to) an index. A unique ID is generally more stable than an index. For example, it may be more useful to identify a contact in Address Book by its identifier (which doesn't change over time) than by its index in the list of contacts (which can change as contacts are added or removed).