Apple WebObjects 3.5 - Manual (Page 196)

Chapter 11 WebScript Programmer’s Quick Reference to Foundation Classes
196
Working With Arrays
NSArray and NSMutableArray objects manage immutable and mutable
collections of objects, respectively. Each has the following attributes:
• A count of the number of objects in the array
• The objects contained in the array
The difference between NSArray and NSMutableArray is that you can’t add to
or remove from an NSArray’s initial collection of objects. That is, insertion and
deletion methods provided for NSMutableArrays are not available for
NSArrays. Although their use is limited to managing static collections of objects,
it is best to use NSArrays wherever possible.
You can create NSArrays with WebScript’s @ syntax for defining constant
objects. For example, the following statements create NSArrays:
id availableQuantities = @(1, 6, 12, 48);
id shortWeekDays = @("Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat");
You can also create NSArrays with creation methods. If you want to create a
static array that contains variables, you have to use a creation method because
you can’t use variables in WebScript’s @ syntax. The following statement creates
an NSArray that contains variables:
id dinnerPreferences = [NSArray arrayWithObjects:firstChoice,
secondChoice, nil];
The variable dinnerPreferences is an NSArray, so its initial collection of objects can’t
be added to or subtracted from. When you need to create an array that can be
modified, use a creation method to create an NSMutableArray. For example, the
following statement creates an empty NSMutableArray to which you can add
objects:
id mutableArray = [NSMutableArray array];
The methods provided by NSArray and NSMutableArray are described in more
detail in the next section.
Commonly Used Array Methods
The following sections list the most commonly used NSArray and
NSMutableArray methods. The methods covered are grouped according to
function.