Creating dictionaries – Apple WebObjects 3.5 User Manual

Page 202

Chapter 11

WebScript Programmer’s Quick Reference to Foundation Classes

202

Creating Dictionaries

The methods in this section are class methods, as denoted by the plus sign (+).
You use class methods to send messages to a class—in this case, NSDictionary
and NSMutableDictionary. For more information on class methods, see
“Sending a Message to a Class” (page 172).

+ dictionary

Returns an empty dictionary. Usually used to create
NSMutableDictionaries. NSDictionaries created with this method are
permanently empty.

// Most common use
id mutableDictionary = [NSMutableDictionary dictionary];

// May not be what you want
id dictionary = [NSDictionary dictionary];

+ dictionaryWithObjects:forKeys:

Returns a dictionary containing entries constructed from the contents
of a speciﬁed array of objects and a speciﬁed array of keys. The two
arrays must have the same number of elements.

id preferences = [NSMutableDictionary

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

+ dictionaryWithObjectsAndKeys:

Returns a dictionary containing entries constructed from a speciﬁed set
of objects and keys. This method takes a variable number of
arguments: a list of alternating objects and keys ending with

nil

id customerPreferences = [NSDictionary dictionaryWithObjectsAndKeys:

seatingPreference, @"seatAssignment",
smokingPreference, @"smoking",
aircraftPreference, @"aircraft", nil];

+ dictionaryWithDictionary:

Returns a dictionary containing the contents of a speciﬁed dictionary.
Usually used to create an NSMutableDictionary from an immutable
NSDictionary.

+ dictionaryWithContentsOfFile:

Returns a dictionary initialized from the contents of a speciﬁed ﬁle.
The speciﬁed ﬁle can be a full or relative pathname; the ﬁle that it
names must contain a string representation of a dictionary, such as that
produced by the

writeToFile:atomically:

method.