Name
NSArray — Mac OS X 10.0
Synopsis
This class manages an immutable ordered collection of
objects.
Objects are stored in an array by reference. That is, the pointer to
the object is stored rather than the object itself. When the object
is added to an array, the array retains it by sending a
retain message to the object. When the array is
released it sends a release message to each of its
members.
There are many methods for querying the contents of the array.
The method objectAtIndex: is commonly used to
access an object at some position in the array. Conversely, we can
determine the index of some object using the method
indexOfObject:, which returns the lowest index of
the member that is equivalent the specified object. To determine the
number of objects contained within the array the
count method is invoked.
To enumerate the contents of an array, create
an NSEnumerator object for the array using one of
two methods: objectEnumerator or
reverseObjectEnumerator. A standard object
enumerator will return the objects in the order that they exist
within the array, while the reverse enumerator will return members
starting from the last object and working its way forward. See the
NSEnumerator class description for more
information on enumerating collections.
Often we want to invoke some method in each member of a collection.
NSArray provides a method that saves us from the
burden of having to enumerate the contents of the array and send the
message manually. This method is
makeObjectsPerformSelector:, which will cause the
method matching the selector to be invoked in each member of the
collection. If you need to invoke a method that takes an argument,
then use the method
makeObjectsPerformSelector:withObject:.
NSArray is an immutable class. The class
NSMutableArray supports ordered collections whose
contents can be changed after initialization.
NSArray is toll-free bridged with the Core
Foundation type CFArray. As such,
NSArray objects can be used interchangeably with
the CFArray pointer type,
CFArrayRef.
