This part of the book provides a quick reference to
Cocoa's primary frameworks: Foundation and
Application Kit. This part starts out with a quick overview of how to
use the Cocoa quick reference to better help you understand its
organization and structure. The chapters in this part
aren't meant to be read from start to finish, but
instead are intended to be used as a reference to keep by your side
while programming.
Chapters in this part of the book include:
Chapter 9, Foundation Types and
Constants
Chapter 10, Foundation
Functions
Chapter 11, Application Kit Types and
Constants
Chapter 12, Application Kit
Functions
Chapter 13, Foundation
Classes
Chapter 14, Foundation
Protocols
Chapter 15, Application Kit
Classes
Chapter 16, Application Kit
Protocols
Additionally, Part II begins with an explanation of How to
Use This Quick Reference, and wraps up with an index (Method Index) that
contains an alphabetical listing of every method in the Foundation
and Application Kit frameworks, called the Method
Index.
How to Use This Quick Reference
Part II crams a great deal of information about Cocoa into a
relatively small space. In this chapter we take a look at how this
information is organized and how to read the quick-reference entries.
Organization of the Quick Reference
Chapter 13 and Chapter 15 cover the classes of the Foundation and
Application Kit frameworks. Chapter 14 and
Chapter 16 contain quick-reference entries for the
protocols of these two frameworks. Within these four chapters
quick-reference entries are arranged alphabetically. Finally, the
Method Index contains an alphabetical listing of every method in the
Foundation framework and Application Kit. Each method name in the
index has a list of classes that implement that method.
Here's how to read a quick reference entry.
Description
Following the title of each quick-reference entry is a brief
description of the class or protocol. Descriptions may be as short as
a couple of lines, or as long as several paragraphs of text.
Hierarchy
Every class in the quick reference has a figure illustrating the
hierarchy of the class, and any protocols adopted by the class or its
ancestors. In the hierarchy figure classes appear as rectangles
containing the name of the class, and formal Objective-C protocols
appear as rectangles with rounded corners. The root object of each
hierarchy (either NSObject or
NSProxy ) is at the left of the figure, with
subclasses extending horizontally to the right. Subclasses are
connected by a solid line, which denotes an inheritance relationship.
The protocols adopted by any class in the hierarchy appear vertically
beneath the class. Note that the hierarchy only shows the
superclasses of a class. Subclasses of the class, if any exist, are
listed after the class synopsis in the
"Subclasses" cross-reference.
Synopsis
The synopsis is the most important part of the class reference,
providing a list of the methods that are part of the class interface.
Additionally, the class synopsis provides a list of methods that a
delegate object might implement, as well as a list of notifications
that the class can post. Each class synopsis begins with the class
interface declaration as it would appear in the class header file.
The interface declaration displays the class name, superclass name,
and any protocols that the class adopts. For example,
NSDate has the following interface declaration in
its class synopsis:
@interface NSDate : NSObject <NSCoding, NSCopying>
Following the interface declaration is a list of methods that are a
part of the class's interface. This includes all
methods that may be declared in a category of a method. The class
interface method list is ended with @end . Following
the class method list is a list of methods a delegate object may
implement, and a list of notifications that instances of the class
may post to the notification center.
Protocol synopses take on two forms, depending on whether the
protocol is formal or informal. Formal protocols
enclose the method list as follows:
@protocol ProtocolName
// Methods
@end
While an informal protocol synopsis appears as a
category interface declaration:
@interface NSObject (ProtocolName)
// Methods
@end
Functional grouping of methods
Methods in the class synopsis are broken up into several optional
categories, within which the methods are listed alphabetically. A
class may have groups of convenience constructors, initializers, and
property accessor methods, in addition to class and instance methods.
Additionally, the synopsis lists methods a class expects its delegate
to respond to, as well as notifications posted by instances of the
class. Method groups are separated in the synopsis with C comments,
such as // Initializers , // Class
Methods , and // Notifications . Protocol
synopses group methods either as instance or class methods. Not every
class has methods that fall under each of these categorizes. The
various categories are as follows (in the same order they would
appear in the class synopsis):
- Convenience constructors
-
Lists any convenience constructors of a class. Convenience
constructors are class methods that combine object allocation and
initialization into one step. By convention, objects returned by
convenience constructor have already been sent an
autorelease method, and will be released at the end of
the event-loop. If you wish to use an object for a longer period of
time you must send a retain message to the
returned object. Generally speaking, convenience constructors very
nearly mirror the initializers of a class. A class may have other
factory methods listed in the Class Methods grouping in addition to
these convenience constructors.
- Initializers
-
This grouping lists all of the initializers of a class, which is any
method that begins with init . When instantiating an
class with alloc , you must initialize the new object
with one of the class's initializers before it is
used. Objects created and initialized in this way have a reference
count of 1, unlike objects returned by convenience constructors,
which have been autoreleased before they are returned.
- Accessor methods
-
This section lists methods that are used to access the properties of
a class. Any instance method that begins with set...
is listed here; these are used to set the property indicated in the
method name. Conventionally, methods used to access properties are
named after the property. For example, NSBezierPath
has the method setLineWidth: to set the line width of
the path. The associated get-property instance method is
lineWidth —the name of the property. Accessor
methods are listed alphabetically by the property name, so that the
"set" methods appear grouped with
their respective property query methods.
- Class methods
-
This section of the synopsis lists all class methods that are not
constructors or accessor methods.
- Instance methods
-
This section lists all instance methods that are not initializers or
accessor methods.
- Implementing methods
-
This section groups methods that implement the same protocol. For
each protocol adopted by the class, there is one subgroup of methods.
- Delegate methods
-
This section lists any methods a delegate of the class may optionally
implement. Delegate methods are not part of the class interface;
generally, they are declared as a category of the root class,
NSObject .
- Notifications
-
This section lists the symbolic names of any notification that the
class may post during its lifetime.
