About NSArray
Like JavaScript arrays, a Cocoa Touch array is an ordered collection
of data, with each element of the array referenced through a zero-based
index number. You can use that index to iterate through both styles in
for repeat loops. Although both objects
have a handful of methods that perform similar tasks with arrays, you have
more restrictions and more possibilities with the NSArray than you do with JavaScript
arrays.
The most important departure is that when you create an NSArray, you have one shot to include elements
in the instance of the array. That instance remains fixed for its life
with respect to its content and order. Methods allow you to create new
NSArray instances that append additional elements to
the original, extract copies of elements from the array, and obtain a copy
of the array sorted according to criteria you devise. To create an array
that has the same type of self-modifying behavior as the JavaScript array,
you can use the NSMutableArray
class.
Arrays are often vital components of iOS apps because they typically
become the data sources for table views. You can write an NSArray to a file (or deliver a file in your app
bundle) and, in a subsequent session, load that file to recreate the
NSArray object for your code to use.
The sorted order of an array determines the sorted order of cells in the
table view.
The NSArray class is far more
adaptable than a C array, whose elements must all be of the same data
type. That restriction is gone from NSArray
Get Learning the iOS 4 SDK for JavaScript Programmers now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.
