Apple WebObjects 3.5 Uživatelský manuál stáhnout pdf (Strana 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.

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Apple WebObjects 3.5 Uživatelský manuál Strana 202