Sends a message specified by a given selector to each object in the set.
Mac Catalyst 13.0+
A selector that specifies the message to send to the set's members. The method must take a single argument of type id. The method should not, as a side effect, modify the set. The value must not be NULL.
The object to pass as an argument to the method specified by aSelector.
The message specified by aSelector is sent, with argument as the argument, once to each member of the set. This method raises an NSInvalidArgumentException if aSelector is NULL.