Exceptions and the Cocoa Frameworks Exceptions in Cocoa are
represented by objects of the NSException class, which is part
of the Foundation framework. The methods of this class allow you
to create exception objects, raise (throw) exceptions with them,
and get the call return addresses related to an exception. The
attributes of an NSException object are the following: name— a
short string that is used to uniquely identify the exception.
The name is required. reason— a longer string that contains a
“human-readable” reason for the exception. The reason is
required. An optional dictionary ( userInfo) used to supply
application-specific data to the exception handler. For example,
if the return value of a method causes an exception to be
raised, you could pass the return value to the exception handler
through You may extract the information in an exception object
and, if appropriate, present to the user in an alert dialog,
perhaps using an NSError object. See “Handling Exceptions” for
information on this subject.