Adding, removing, and modifying entries – Apple WebObjects 3.5 User Manual

Page 204

Chapter 11

WebScript Programmer’s Quick Reference to Foundation Classes

204

– isEqual:

Returns YES if the speciﬁed object is a dictionary and has contents
equivalent to the receiver; NO, otherwise. Two dictionaries have
equivalent contents if they each hold the same number of entries and,
for a given key, the corresponding value objects in each dictionary
satisfy the

isEqual:

test.

– objectForKey:

Returns the object that corresponds to a speciﬁed key. For example,
the following code excerpt produces the NSString

sectionPreference

with

the contents “non-smoking”:

id preferences = [NSMutableDictionary

dictionaryWithObjects:@("window", "non-smoking", "747")
forKeys:@("seatAssignment", "section", "aircraft")];

id sectionPreference = [dictionary objectForKey:@"section"];

Adding, Removing, and Modifying Entries

Warning:

The following methods are not supported by NSDictionary. They are

available only to NSMutableDictionary objects.

– setObject:forKey:

Adds an entry to the receiver, consisting of a speciﬁed key and its
corresponding value object. If the receiver already has an entry for the
speciﬁed key, the previous value for that key is replaced with the
argument for

setObject:

. For example, the following code excerpt

produces the NSMutableDictionary

dictionary

with the value “non-

smoking” for the key “section” and the value “aisle” for the key
“seatAssignment.” Notice that the original value for “seatAssignment”
is replaced:

id dictionary = [NSMutableDictionary dictionaryWithDictionary:

@{"seatAssignment" = "window"}];

[dictionary setObject:@"non-smoking" forKey:@"section"];
[dictionary setObject:@"aisle" forKey:@"seatAssignment"];

It is an error to specify

nil

as an argument for

setObject:

forKey:

. You can’t

put

nil

in a dictionary as a key or as a value.

– addEntriesFromDictionary:

Adds the entries from a speciﬁed dictionary to the receiver. If both
dictionaries contain the same key, the receiver’s previous value for that
key is replaced with the new value.

– removeAllObjects

Empties the dictionary of its entries.